Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6, 1265-1274 2024 Publisher: Learning Gate DOI: 10.55214/25768484.v8i6.2236 © 2024 by the author; licensee Learning Gate © 2024 by the author; licensee Learning Gate * Correspondence: thanhvan@sgu.edu.vn The adjustment of the us strategy towards Asean in recent years and the response of the Mekong sub-region countries Tran Thi Thanh Van1* 1Saigon University, 273 an Duong Vuong Str., Ho Chi Minh City, Vietnam; thanhvan@sgu.edu.vn (T.T.T.V.). Abstract: The article analyzes the strategic changes of the US in Southeast Asia in recent years in the context of increasingly fierce competition between major powers and many hot spots of disputes in the region that have not shown signs of cooling down. The US's interest in and actions towards Southeast Asia has been adjusted towards greater engagement, not only with the traditional region (island Southeast Asia) but also the Mekong Sub-region, to prevent China's growing influence. The US's strategic adjustments have had certain positive and negative impacts on the Mekong Sub-region countries in planning and implementing their foreign policies, aiming to create a balance of influence between major powers. To optimize advantages, in the coming time, the Mekong Sub-region countries need to strengthen regional connectivity, and interweave the interests of major powers to promote cooperation but also avoid being caught up in the vortex of great power competition in the region. Keywords: China, Mekong Sub-region, Southeast Asia, US. 1. Introduction The world is currently entering a period of rapid change with enormous changes associated with the fourth industrial revolution and fierce strategic competition between countries. In the early 20s of the 21st century, the world was deeply affected by the COVID-19 pandemic, changing the economic and social situation, and forcing major countries to make adjustments in foreign and domestic policies. In the context of deep international integration, the national security of each country is influenced by the complex, rapidly and profoundly changing regional situation. In addition, competition between major countries is fierce and increasingly large-scale. Southeast Asia is where many interests and strategic priorities of major countries are present and concentrated. This is a dynamic region with an important strategic position, and also a place with many complicated "hot spots" in terms of security and sovereignty disputes. In the context of the US continuing to implement the policies of the Asia-Pacific pivot strategy under President Joe Biden, the role of Southeast Asia in the strategy of the world's number 1 superpower is becoming increasingly important. The change in US strategy towards Southeast Asia creates both opportunities and challenges for the countries of the Mekong Subregion. This is a region with half of the members of the Association of Southeast Asian Nations (ASEAN), with important geo-strategic values. The new situation requires the countries of the Mekong Subregion, including Vietnam, to have a thorough view to plan policies and implement appropriate actions. Through the study of the movement of US-ASEAN relations in the early 21st century, the article contributes to clarifying the essence of ASEAN's role in the US's "pivot to Asia-Pacific" policy. From there, we have an overall assessment of this relationship in terms of achievements, limitations, and 1266 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 1265-1274, 2024 DOI: 10.55214/25768484.v8i6.2236 © 2024 by the author; licensee Learning Gate characteristics; pointing out the impacts of this relationship on the ASEAN region as well as the Mekong Subregion countries in particular. In terms of content, the article focuses on studying the US-ASEAN relationship in the early 21st century. Movements in the fields of politics, diplomacy, security, defense, economy - trade, and some other fields. In terms of space, the article studies the relationship of a country with a regional organization (US- ASEAN), therefore, we only focus on the research process of developing the US-ASEAN relationship in the US-Southeast Asia space. In terms of time, the research focus of the thesis is determined from 2001 to the end of 2023. 2. Literature Review The US-ASEAN strategic shift has attracted widespread research attention from international scientists. Its evidence is the massive volume of research works by international scholars on many aspects. Among them are some typical works that we have accessed and exploited to complete the article: A prominent work is the book by Nguyen Huy Hoang "Southeast Asia in the US Indo-Pacific Strategy", published in 2021. The author analyzes the geopolitical and geostrategic position of the Asia- Pacific region as extremely important to the US. Therefore, the US is determined to "Pivot" to Southeast Asia with the aim of (i) Strengthening allied and near-allied relations with Thailand, the Philippines, and Singapore, focusing on strengthening security relations; (ii) Attracting partner countries such as Indonesia, Vietnam, Malaysia, Brunei, focusing on economic, trade and investment cooperation; (iii) Continue to maintain contact with countries that are still in conflict, even opposing the US such as Myanmar, Cambodia, Laos through economic aid, lifting the embargo, etc.; (iv) Strengthen cooperation with ASEAN, establish multilateral cooperation mechanisms with ASEAN; (v) Expand activities related to ideology and value concepts, emphasizing the role and importance of human rights and democratic value concepts; and finally, focus on shifts from the Pacific to both the Pacific and Indian Oceans. Tran Khanh's book (2014), "US-China strategic cooperation and Competition in Southeast Asia in the first three decades after the Cold War", World Publishing House. The book explains the trends in international relations in Southeast Asia as well as the US-China relationship in contemporary history, this relationship has the deepest and strongest impact on the trend of cooperation and development in Southeast Asia in particular, the world order in general in the first three decades of the 21st century. In the research of scholar Carmia Colette Carroll with the content "US-ASEAN relations under the Obama Administration 2009 - 2011" published by Georgetown University Publishing House, Washington DC in 2012, the author analyzed the strategic adjustments in President Obama's first term. While under the previous Bush administration, US-Southeast Asia relations were tense because President Bush considered Southeast Asia as the second front in the war on terrorism after the September 1, 2001 event, US-Southeast Asia relations improved under Obama in the economic, political, and cultural fields. With this study, author Carroll has a comparative view of US-Southeast Asia relations under Presidents Bush and Obama. In addition, the article also accesses data and interpretations from articles by Dao Ngoc Dinh (2022), "Impact of US Policy on Southeast Asian Security", Journal of Political Theory; Bui Thanh Tuan (2021), "Mekong-US Partnership: foundation and development direction for the Mekong Subregion", Communist Magazine; Blinken, A. J. (2021), "The United States and the Friends of the Mekong: Proven Partners for the Mekong Region", Retrieved from U.S. Department of State; Center, E. W. (2020), “The Mekong Matters for America”, Retrieved from JSTOR; Spokesperson (2019), “Strengthening the U.S. – Mekong partnership”, Retrieved from U.S. Embassy & Consulate in VietNam… In general, the works have analyzed the process of changing the US strategy towards Southeast Asia in the early years of the 21st century and the impacts on the regional situation. Based on the above 1267 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 1265-1274, 2024 DOI: 10.55214/25768484.v8i6.2236 © 2024 by the author; licensee Learning Gate documents, we will analyze and clarify the role of Southeast Asia in the US “pivot” policy, and analyze the impacts on the Southeast Asian region in general and the Mekong sub-region in particular. 3. Methodology The article selectively uses modern international relations theories in assessing a country's policies towards countries and regions. The approach of the article is historical. The main research methods of the thesis are historical, logical methods, and international relations research methods. In addition, we also apply and combine other research techniques such as analysis, synthesis, comparison, etc. 4. Results and Discussion 4.1. The US's Strategic Shift Towards ASEAN From a geo-economic perspective, ASEAN plays an important role in the strategy to implement the US Indo-Pacific Strategic Vision (FOIP). ASEAN is the third largest economy in Asia after China and Japan. This region is a large market with an area of over 4.4 million km2, a population of nearly 650 million people, total GDP of trade exchange, and international investment attraction in 2018 reached 2.98 trillion USD, 2.82 trillion USD, and 152.7 billion USD respectively (ASEAN Secretariat 2020). By 2019, those figures had increased to 3.17 trillion USD, 2.82 trillion USD, and 160.6 billion USD respectively (ASEAN Secretariat 2020). In addition, the integration process of ASEAN marks a milestone, an important stage with the declaration of the successful construction of the ASEAN Community (AC), including the ASEAN Economic Community (AEC) in 2015. However, the AEC is not the end of regional cooperation and integration, but the ASEAN countries will continue the process of closer and deeper economic integration to move up to a new level. This is demonstrated in the member countries' adoption of the "Master Plan for ASEAN Community Building 2025" including the master plan for building AEC 25 (Hoang N.H 2021). Southeast Asia is a huge investment market, consuming a large amount of goods, and bringing high profits to the US. Countries in the region are mainly developing countries, lacking capital and having rather backward technology, but cheap labor, and are having policies to stimulate foreign investment, especially in high-tech industries (automobile, computer, mobile phone manufacturing, etc.) which are the dominant fields of the US and developed capitalist countries. Moreover, Southeast Asian countries are forming a wealthy middle class, which further increases the purchasing power of the market. Countries with transitional economies in the region will participate more in the vertical division of labor system, where the "value chain" of high-tech products is dominated by the West and Japan. This brings high profits to foreign investors and benefits domestic consumers. Regarding political and security interests, ASEAN is important in the US's Asia-Pacific security strategy. At the same time, ASEAN is also one of the regions with the densest military forces, the greatest potential for military development, and the most serious nuclear proliferation problem in the world. The US is very concerned about the proliferation of weapons of mass destruction in Asia, such as the nuclear issue in North Korea Iran, India, and Pakistan. In addition, Southeast Asia has become the "second front" in the US's global war on terrorism. After the September 11, 2001 event, the US government put counter-terrorism at the heart of its national security strategy. The US believes that the Islamic terrorist force in South Asia and Southeast Asia poses a serious threat to US security interests in the Asia-Pacific region. On the other hand, returning to Southeast Asia, the US wants to implement a common strategy of strengthening ties with some traditional allies in the region. Many countries in East Asia and Southeast Asia are traditional allies of the US (Japan, South Korea, the Philippines, Thailand, Singapore) and cooperate closely with the US in the military field. Other countries such as Indonesia and Vietnam have important common interests with the US and are likely to become closer security and strategic partners in the coming years. Returning to Southeast Asia, the US will not only resume old relations but also improve and develop relations with new allies such as India, build a security belt from Northeast Asia to 1268 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 1265-1274, 2024 DOI: 10.55214/25768484.v8i6.2236 © 2024 by the author; licensee Learning Gate Southeast Asia, reach out to the Indian Ocean, and build an Asian strategic alliance that is beneficial to the US, including Japan, South Korea, India, and ASEAN. The position of Southeast Asia in the US's Asia pivot strategy is also reflected in the organization's contribution to regional cooperation, especially in the Asia-Pacific region. ASEAN has played an important role as a center for reconciling disagreements and conflicts between countries in the region such as the territorial dispute between Malaysia and the Philippines, the maritime sovereignty dispute between Malaysia and Indonesia, or promoting a political solution to the Cambodia issue. Outside the region, ASEAN contributes to promoting the economic integration process through the signing and implementation of trade agreements with most major partners such as China, Japan, South Korea, India, and Australia (Hoang N.H 2021). The United States has expressed its support and appreciation for the centrality of Southeast Asia and ASEAN in the US-led regional security architecture and has given ASEAN more power in Washington’s FOIP Vision Strategy (Chongkittavorn, K. 2018). The United States and ASEAN share common values, and ASEAN is a key partner in promoting the values and policies in the FOIP, including freedom of navigation, market economy, good governance, and respect for a clear and transparent rules-based order. Notably, the United States respects ASEAN’s consensus-based decision- making approach and supports a cohesive ASEAN with an increased voice in the region as a whole and in the current Asia-Pacific and broader Indo-Pacific cooperation structures. The importance of ASEAN in the FOIP Vision and the US Indo-Pacific Strategy is reflected in Washington’s commitment to recent activities of ASEAN-based multilateral institutions such as the EAS, ARF, and the ASEAN Defense Ministers Meeting Plus (ADMM+). Beyond the regional level, the US has also strengthened defense and security cooperation with many ASEAN members, including strengthening alliances with the Philippines and Thailand, strengthening the Singapore partnership, expanding new relationships with Vietnam, Indonesia, and Malaysia, maintaining engagement and strengthening the foundation with Brunei, supporting Laos’ integration into ASEAN, and building relationships with the Cambodian military. Southeast Asia is an important part of the Indo-Pacific Strategy and the FOIP Vision. From the early stages of drafting this strategy, US policymakers recognized that Southeast Asia would be one of the focuses of the plan and that ASEAN was well placed to contribute to ensuring the successful implementation of the FOIP Vision of the Indo-Pacific Strategy. During an informal meeting with ASEAN Defense Ministers on the sidelines of the Shangri-La Dialogue in June 2018 in Singapore, Secretary of Defense James Mattis also emphasized that ASEAN centrality is an important factor for the success of the Indo-Pacific strategy. Also, at the Indo-Pacific Business Forum at the US Chamber of Commerce in July 2018, US Secretary of State Mike Pompeo affirmed in his speech that: “ASEAN is truly at the heart of the Indo-Pacific region and plays a central role in the Indo-Pacific vision that the US is building” (ASEAN Secretariat 2020). Along with the views declared by US politicians, in its foreign policy, Southeast Asia has always been considered one of the regions with influence and significance to the interests of the US as well as its allies. In the FOIP Strategy, the US recognizes the importance of the geostrategic, geopolitical, and geoeconomic position of Southeast Asia and believes that these will be the factors that ensure the US can successfully implement FOIP in the Indo-Pacific region. In addition, geographically, Southeast Asia is located at the center of two important sea regions, the Pacific and the Indian Oceans. Furthermore, the Indo-Pacific Strategy to realize the US FOIP Vision emphasizes the maritime sector - a sector in which Southeast Asia plays a very important role due to the world's vital sea trade routes passing through, with traffic accounting for more than one-third of the total global cargo volume, along with other strategic sea routes such as the Strait of Malacca and the Sulu Sea, both in Southeast Asia. Geopolitically, Southeast Asia is also a region with long-standing US allies, namely Thailand and the Philippines, as well as several other important strategic partners such as Indonesia, Singapore, and Vietnam. Therefore, this is considered an important basis for the US to promote the Indo-Pacific 1269 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 1265-1274, 2024 DOI: 10.55214/25768484.v8i6.2236 © 2024 by the author; licensee Learning Gate Strategy to implement the FOIP Vision with other countries in the region. ASEAN is the center of many high-level cooperation mechanisms such as ARF, ADMM+, EAS, US-ASEAN Leaders Summit. The US can make the most of these mechanisms to participate in the field of humanitarian assistance and disaster relief (HADR), enhance security capacity, effectively reform governance, and add more initiatives for the Southeast Asian region. Another important point that is perhaps crucial in FOIP is that the US considers Southeast Asia as an important front in the Indo-Pacific region to control China's growing influence in this region. In terms of economics, in addition to its role as a platform for political and security dialogues, ASEAN also plays an important role in the US economy. Southeast Asia has the third largest population in the world after China and India with nearly 650 million people, and is the fifth largest economy in the world. If considered within the scope of the Indo-Pacific region where the US proposed and implemented the Indo-Pacific Strategy, Southeast Asia has a greater position and significance in terms of economy and strategy for the US to invest. The US has a larger investment flow from ASEAN than from China and India combined. About 42,000 US companies export goods and services worth over 100 billion USD annually to ASEAN. This helps create more than half a million jobs for the US. The potential for trade with ASEAN is very promising because the economies in the region have among the highest growth rates in the world. Regarding the US approach to ASEAN's role in the Indo-Pacific Strategy, on November 3, 2019, the US State Department officially released a 30-page report titled "Free and Open Indo-Pacific: Advancing a Shared Vision" to specify the contents of the Indo-Pacific Strategy since President Donald Trump announced it at the APEC Summit in November 2017 in Da Nang, Vietnam. Accordingly, the US FOIP Vision focuses on three main goals: promoting shared prosperity, good governance with the promotion of democratic and liberal values, and ensuring security and peace in the region. These US goals are also the goals that ASEAN wants to build, especially ensuring security, peace, and prosperity in the region. Since taking office, US President Joe Biden has demonstrated a continuation of the policy commitments of previous administrations to the Indo-Pacific region. The region connecting the two oceans, with Southeast Asia at the center, continues to be a top priority in US policy. However, the approach to the region has been adjusted, and the focus on cooperation in the new period is also clearly taking shape. On February 12, 2022, the President officially announced the "Indo-Pacific Strategy", affirming that the US will emphasize "meaningfully expanding" its stronger presence in Southeast Asia. At the same time, he affirmed that he will contribute to an ASEAN with an increasingly strong and unified voice (The White House 2022). Despite the similarities in goals, US President Joe Biden's approach to the region is still different from that of President Donald Trump. This shows the adjustment and adaptation of the US strategy to the challenges after a period of implementing the Indo-Pacific vision. First, President Joe Biden affirmed the importance of interaction and coordination with countries in the region to achieve common goals. The US will not look at Asia simply as an arena of geopolitical competition but as the approach of US allies in the region (specifically Australia, Japan, South Korea, etc.). The US also emphasizes the purpose of not only strengthening its role but also consolidating and aiming for the common interests of the region. The goals set require cooperation between countries with a common vision in the region. The role of allies and partners is emphasized, deciding the success of the goals. This has been demonstrated through a series of moves by US President Joe Biden since taking office to strengthen and enhance relations with allies and partners in the region, as well as the US's re-engagement in multilateral forums and processes here (Van, N.K; Trung, N.X, 2023). In particular, the view of putting ASEAN at the center of the Indo-Pacific Strategy was put forward under President Donald Trump, when the US identified "ASEAN as the backbone of regional politics" and expressed support for the stability and prosperity of Southeast Asia. For some countries in the region, the Donald Trump administration affirmed the importance of allied relations with Thailand and the Philippines, as well as the US's priority partners in the region such as Indonesia, Malaysia, and 1270 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 1265-1274, 2024 DOI: 10.55214/25768484.v8i6.2236 © 2024 by the author; licensee Learning Gate Singapore. In addition to ensuring comprehensive support for ASEAN countries, from energy, cybersecurity, and digital trade to promoting business activities, the US President Donald Trump administration has also committed to actively participating in ASEAN institutions such as the East Asia Summit (EAS), the ASEAN Regional Forum (ARF), and the ASEAN Defense Ministers Meeting Plus (ADMM+). During the Biden presidency, ASEAN's role in regional security and prosperity continues to be highlighted, serving as a driving force for important forums such as EAS, ADMM+, ARF, and the Expanded ASEAN Maritime Forum (EAMF) (ASEAN 2020). In particular, US President Biden wishes to promote and upgrade partnerships in the region. In May 2022, the US hosted 10 ASEAN countries in Washington DC within the framework of the Special Summit commemorating the 45th anniversary of relations between the two sides. Here, the US-ASEAN relationship was agreed to be upgraded to a comprehensive strategic partnership in November 2022 (US Embassy and Consulate General in Vietnam 2022). In addition, President Joe Biden sent a message that the US will respect the policies and choices of ASEAN countries, supporting ASEAN's central role in regional issues. This approach shows that the US is well aware of the determination of Southeast Asian countries to pursue an independent, self-reliant, self-determined, balanced foreign policy and not to be drawn into the strategic competition between the US and China in the region. Accordingly, the US respects and supports the aspirations of countries in the region to become a strong, independent, and leading ASEAN Community, or a peaceful Southeast Asia without nuclear weapons... The fact that the US is standing from the perspective of ASEAN countries to build its regional policy is considered a guarantee of a more cohesive and sustainable bilateral relationship in the future. Regarding the force aggregation, the strategic allies Japan, South Korea, Australia, Thailand, and the Philippines are key elements in the US-led force aggregation under the “Axis and Spokes” structure. To maintain its position, the US has focused on consolidating security treaties since the Cold War, tightening relations with strategic allies; expanding and enhancing cooperation with many partners in the Indo-Pacific region, especially Southeast Asia (with Indonesia, Singapore, Malaysia and Vietnam); continuing to consolidate and redeploy forces and military activities in the region; actively participating in and promoting security cooperation in several forums and mechanisms, such as APEC, ASEM... The levels in this network of allies and partners aim to ensure the maximum value, interests, and strategic advantages of the US in the region. In addition, the US does not "rigidly divide" but proactively seeks and builds relationships with new partners, attracting them to join the US-led and -dominated force group with high counterbalance such as the "Quad", the AUKUS Trilateral Military Alliance, the SALPIE Initiative... to increase military presence, coordinate with the US to restrain China in the East Sea; at the same time, strengthen strategic competitiveness in the Indo-Pacific, including Southeast Asia (Dinh, D.N 2022). The increasing presence of the US in regional hotspots is the clearest evidence of the world's No. 1 power's growing interest in the region and its strategy to prevent China's expansion to the southern region. Firstly, in the East Sea hotspot, the US maintains and implements the stance of "not taking sides in the East Sea dispute" but rejects China's "nine-dash line" claim, supports the 2016 Permanent Court of Arbitration (PCA) ruling, and promotes the role of international law, including UNCLOS 1982. Even at many multilateral forums, the US criticizes China for not complying with international law and for its coercive actions in the East Sea. Notably, on January 13, 2022, the US State Department published Report No. 150 on maritime boundaries, rejecting the geographical and historical basis of China's claims in the East Sea; Calls on China to comply with UNCLOS 1982, the PCA ruling in 2016, and end illegal and coercive activities in the East Sea. At the same time, to increase pressure, the US has increased its military presence, demonstrating its deterrent power, and increasing the heat of hotspots in Southeast Asia and the broader Indo-Pacific. The US has carried out freedom of navigation operations (FONOPs) and coordinated with allies (UK, France, Germany, Japan, Australia, etc.) to conduct large and small-scale patrols and exercises in the 1271 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 1265-1274, 2024 DOI: 10.55214/25768484.v8i6.2236 © 2024 by the author; licensee Learning Gate East Sea to compete directly with China. Notably, the FONOP on July 12, 2021, coincided with the 5th anniversary of the Permanent Court of Arbitration's ruling on the East Sea issue (2016); the FONOP on September 8, 2021, the US Navy ship entered the 12-nautical mile area of Vanh Khan Reef, Truong Sa archipelago after China's revised Maritime Traffic Safety Law took effect. The US has also deployed more warships, short-range and medium-range ballistic missiles... in the region; accelerated the redeployment of forces, and established new military bases in Southeast Asia. Currently, the USINDOPACOM alone has equipped more than 2,000 aircraft, and 200 warships with more than 370,000 troops; the largest deployments are in Japan and South Korea and on a smaller scale in Singapore, the Philippines, and Australia (Cuong 2021). Next, in the Mekong Subregion, an area that previously received little attention from the US, the US has recently increased its presence, focusing on promoting the implementation of the Mekong-US Partnership (MUSP) mechanism, investing resources to deal with non-traditional security challenges, and resolving sensitive cross-border environmental issues that contain conflicts between China and the countries downstream of the Mekong River. MUSP promotes the values of transparency, and free and fair competition, contributing to limiting challenges, promoting stability, sustainable development, and bringing prosperity to the region (Tuan, B.T 2021). Although the competition between the US and China in the Mekong Subregion is not as tense and fierce as in the East Sea, with the US's strategic "reflection" and the return to the region of the "reigning" No. 1 superpower, the Mekong Subregion is likely to become a security hotspot in Southeast Asia. During the political crisis in Myanmar, after the coup on February 1, 2021, the US has continuously used diplomatic pressure and sanctions on the Myanmar military government. In terms of diplomacy, the US called on China to play a "constructive" role in resolving the increasing violence in Myanmar. Notably, in the Joint Statement after the first in-person Quad Summit on September 24, 2021, the US and its allies called for an end to violence, the release of political prisoners, the early restoration of democracy, and the immediate implementation of the ASEAN Five-Point Consensus Statement. This, on the one hand, demonstrates the importance of ASEAN's role, and on the other hand, also creates considerable pressure on ASEAN in dealing with this political crisis. 4.2. Impact and Policy Implications for the Mekong Sub-Region Countries The Mekong sub-region (including the five countries of Cambodia, Laos, Myanmar, Thailand, and Vietnam) is a geo-strategic region made up of outstanding geo-political, geo-security, and geo-economic values. The countries in the Mekong sub-region share similarities in history, culture, and the great advantages of the Mekong River, while also being affected by the intertwined impacts of factors affecting the geo-strategic value of this region. In particular, the competition and strategic adjustments of major countries have led to changes in the regional situation. The Mekong sub-region occupies an important position in the strategies and foreign policies of major powers, including the United States. In recent years, this place has witnessed fierce competition and establishment of influence between the world's leading superpowers, especially between the United States and China. This trend is likely to have more complicated developments in the coming time, posing a problem for countries in the region to respond to ensure national interests and sustainable development. The Mekong countries are important diplomatic, economic, and security partners of the United States. The United States has allocated more than $4.3 billion in development assistance to bilateral and regional initiatives in the Mekong River over the past 12 years (Blinken, A. J 2021). In 2009, the Lower Mekong Initiative was established by the US State Department to promote regionalism and sustainable development in the Mekong region. As of 2019, the US government has provided more than $120 million for LMI programming (Center, E. W 2020). However, the US foreign policy towards Southeast Asia has been somewhat inconsistent, especially in the Mekong Subregion with unclear commitments and lack of emphasis under President Obama, which has allowed China to find loopholes in its “backyard” and is succeeding in its efforts to strengthen its cooperation mechanism. It was not until the 1272 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 1265-1274, 2024 DOI: 10.55214/25768484.v8i6.2236 © 2024 by the author; licensee Learning Gate US launched its Free and Open Indo-Pacific Strategy in 2017 that the region witnessed a significant shift in US commitment. The US’s increased engagement in the Mekong River issue aimed to increase its influence and politicize the Mekong River water resources issue as part of its efforts to contain China’s growing influence in the region. The Lower Mekong Initiative was revived as a tool for the US to re-engage with the subregion. Subsequently, at the 10th LMI Ministerial Meeting in 2017, the “Mekong Water Data Initiative” was established to promote the sharing and use of Mekong River system data by the Mekong River Commission (MRC). In 2018, US Secretary of State Mike Pompeo reaffirmed the LMI as a key driver to promote connectivity, economic integration, sustainable development, and effective management (Partnership, M.U. 2018). In 2019, the US continued to propose an investment of 15,000 USD for research projects related to the Mekong Subregion (Partnership, M.U. 2019). In addition to research cooperation projects, the US also increased support for other initiatives such as fighting transnational crime, sharing data on Mekong River water resources, Asia EDGE, Asian Young Leaders, etc. This shows that the LMI under the Trump administration has become more vibrant. After the first Mekong-US Partnership Ministerial Meeting, the US announced a total commitment of 156.4 million USD for a series of initiatives under the US-Mekong Partnership, including 52 million USD to support economic recovery after the Covid-19 pandemic; 55 million USD to combat transnational crime; 33 million USD to develop energy markets under the Asia EDGE framework; 6.6 million USD to improve energy infrastructure and markets in the Mekong Subregion; and 2 million USD to combat human trafficking (Spokesperson, O 2019). Through the Mekong-US Partnership, the US government hopes to build a sustainable and long-term cooperation process to ensure a Mekong sub-region that develops in peace, security, and prosperity. US-Mekong cooperation initiatives have contributed to information sharing among US agencies operating in the basin and with the governments of countries in the Mekong basin. The constructive role of the US will contribute to promoting cooperation among countries in the basin, towards the establishment of the “Mekong Standards”. It can be seen that the US's increased cooperation with the Mekong Sub-region countries marks a return to the regional leadership role that the US lost from China. The US's policy in the Sub-region is more competitive and directly confronts China than before, which will be a boost to solve the challenging problems of the countries in the Sub-region. The US demonstrates its ambition in this region with a coordinated plan, shaping a direction in line with national interests. This can facilitate economic interdependence and deepen trust and a sense of shared interests. The US's increased connectivity in the Sub-region is an important step to narrow the division within the group and foster true community building. In the coming time, the Mekong Sub-region countries need to have appropriate policies to take advantage of the US's strategic changes to create a balance and promote development cooperation in the region. First of all, the Mekong sub-region is one of the few sub-regions in the world that has a full range of intra-regional cooperation mechanisms as well as cooperation mechanisms with many external partners. These mechanisms contribute to the formation of transport axes, connecting corridors, and economic linkages; creating more resources for sustainable socio-economic development. However, some areas of cooperation are still overlapping and ineffective due to the lack of coordination between mechanisms. In the coming time, countries in the sub-region need to be aware of the problem to resolve disagreements and come closer together. This will contribute to diversifying resources for cooperation and driving force for the socio-economic development of countries in the sub-region. Second, according to researchers' forecasts, at present and in the near future, the US-China strategic competition will continue to be fierce; the war between Russia and Ukraine will continue to be complicated and unpredictable; The US's active policy in Southeast Asia is changing in many ways that benefit the countries of the Sub-region. Therefore, countries need to actively seek to promote cooperation with the US in all fields, especially in the field of defense and politics, to create a balance in the region. Countries 1273 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 1265-1274, 2024 DOI: 10.55214/25768484.v8i6.2236 © 2024 by the author; licensee Learning Gate in the region also need to have accurate and timely forecasts of policy changes, especially in the context of the upcoming US election, in order to have appropriate countermeasures. Third, in recent years, thanks to its strategic location and growth potential, the Mekong River Basin has attracted the attention of major powers and development partners, including the United States, China, Japan, India, and the European Union. Cooperation mechanisms among riparian countries and with external partners have provided a platform to discuss regional issues, especially water resources management, economic development and integration into regional and global markets, regional connectivity, and addressing common challenges. To create a strategic balance, the sub- regional countries need a broader relationship, including major countries such as the United States, China, Japan, South Korea, India, etc., participating in stronger cooperation in the region to resolve the difficult situation that the lower Mekong countries are facing. The US, Japan, South Korea, and China's increased cooperation with the Mekong sub-region countries not only benefits the countries in the region but also opens up more options to enhance economic development. 5. Conclusion In summary, along with the shift in US strategy, US-ASEAN relations have entered a new phase, more substantial, more effective, strengthening strategic partnership, for mutual benefit, for peace and stability in the world. This is creating changes that are beneficial to both the US and ASEAN. The US has more favorable factors and important agents to implement the Indo-Pacific policy. ASEAN has a more favorable position in balancing foreign relations, towards a united, stable, and prosperous Community, from which it can enhance and demonstrate more strongly its central role in regional issues and structures in Southeast Asia as well as in the wider Indo-Pacific region. For the Mekong sub- region countries, in the coming time, they can promote relations with the US to create a major power balance in the region. It can be seen that the US has a new approach as well as important adjustments in its foreign policy in the Southeast Asian region. The US focuses on coordination between the US and Southeast Asian countries in both policies and actions for common goals. At the same time, the US respects the central role of ASEAN as well as the organization's autonomy and self-determination on regional issues. The US strengthens cooperation with ASEAN in bilateral relations with countries in the region and upgrades these relationships. For example, the US has upgraded its cooperative relationship with ASEAN to a comprehensive strategic partnership (November 12, 2022); upgraded its bilateral relationship with Vietnam to a comprehensive strategic partnership (September 10, 2023), the US and Thailand signed an agreement to promote the expansion of the strategic partnership (July 10, 2022), the US is promoting further strengthening the strategic partnership with Laos, etc. With this new approach, the US and ASEAN as well as the US and member countries in the region have expanded the framework of cooperation areas and moved towards practicality. The US-ASEAN relationship has entered a new phase, more substantial, and more effective, strengthening the strategic partnership, for mutual benefits, for peace and stability in the world. In addition to traditional security areas, an important driving force in cooperation between the US and ASEAN is towards non-traditional security issues, human security such as cooperation on maritime security, water security, economic security, food security, etc. In particular, US cooperation to support countries in the region to recover from the COVID-19 pandemic, support the Mekong Sub-region to overcome the consequences of climate change, etc. has shown a bright new picture of the prospects and potential in the relationship between the US and Southeast Asia. This is creating favorable changes for both the US and ASEAN. The US has more favorable factors and important agents to implement the Indo-Pacific policy. ASEAN has a more favorable position in balancing foreign relations, towards a united, stable, and prosperous Community, from which it can enhance and demonstrate more strongly its central role in regional issues and structures in Southeast Asia as well as in the wider Indo-Pacific region. For the Mekong sub-region countries, in the coming time, they can promote relations with the US to create a major power balance in the region. 1274 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 1265-1274, 2024 DOI: 10.55214/25768484.v8i6.2236 © 2024 by the author; licensee Learning Gate Copyright: © 2024 by the authors. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). 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