In recent years, China’s inventive engineering feats have allowed it to create more than 3,200 acres of new land in the South China Sea. The result has been to heighten tensions and allow Chinese forces to more easily project military power across the region.

Beijing’s moves have prompted Washington to counter Chinese assertiveness by forging a new strategic alignment in the region—one in which China dominates the South China Sea from the north, the United States and its partners do so from the east and west, and the states of continental Southeast Asia remain neutral or lean toward Beijing in the intensifying U.S.-China strategic competition. This alignment will further U.S. goals: to continue to mount a forward defense, to keep the seas and skies free, and to promote prosperity and the spread of democracy.

This new strategic map of Southeast Asia actually began to take shape during the Bush administration, which initially launched the effort to move beyond America’s traditional hub-and-spokes alliance model in the Asia-Pacific. But the new map’s contours truly began to crystallize earlier this year, when the Philippines’ Supreme Court ruled as constitutional a new defense agreement with the United States. Thanks to the Enhanced Defense Cooperation Agreement (EDCA), American power projection capabilities will be regularly present in the Philippines for the first time since the early 1990s.

During the George W. Bush administration, U.S. forces in the Philippines were focused primarily on aiding the Philippine military in its counterterror fight. Now, the two militaries will increasingly exercise and train across a broad spectrum of military operations, from the low end to the high. Importantly, American access to four airbases (with potentially more to be made available at a later date)—especially those on Luzon and Palawan—will make U.S. air power “resident” in Southeast Asia.

This access will allow for more frequent, more sustained flights over the South China Sea, including over the disputed Spratly Islands and Scarborough Shoal. Importantly, the Air Force’s presence on Luzon, perhaps to be followed by regular naval rotations in Subic Bay, will put the United States in a better position to quickly seal up the Luzon Strait, which links the South China Sea to the Philippine Sea and the wider Pacific Ocean.

The U.S. military’s enhanced ability to loiter in and over the South China Sea, moreover, will facilitate more effective efforts to track Chinese submarines sailing from the PLAN’s underground naval base on Hainan island. Navy P-8s are now regularly deploying to Singapore and, although without regular access, they have conducted patrols from Malaysia as well. American littoral combat ships are rotating through Singapore, at the South China Sea’s western extremis, and the city-state has also quietly built the only Asian port outside of Yokohama at which an American aircraft carrier can dock. The USS John C. Stennis tied up there for a few days in April.

Even if Beijing’s island-building campaign succeeds in turning the South China Sea into a Chinese lake, it will be one in which Chinese forces are constantly monitored and from which they can only depart with implicit American acquiescence.

Then again, China may see its efforts in the South China Sea blunted. The Obama administration’s decision to lift the decades-old arms embargo on Vietnam is instrumental here. In the near term, this could lead to sales of intelligence, surveillance and reconnaissance equipment as well as patrol boats to allow Hanoi to better keep an eye on goings-on in the western South China Sea. Over the longer term, American defense contractors may have their sights set on sales of fighter aircraft and attack helicopters. Vietnam already flies modern Russian fighter jets and is expecting delivery this year of its sixth and final Kilo-class submarine—submarines so quiet that the U.S. Navy refers to them as “black holes.” If the Chinese Navy wants to have its way in the South China Sea, it will have to dedicate resources to tracking those subs, a task with which the PLAN has limited experience.

When China moved a massive oilrig, the Haiyang Shiyou 981, into Vietnam’s exclusive economic zone in 2014, Vietnam had limited options to respond, at either the low end or the high. With a maturing coast guard, navy and air force, Vietnam will become an increasingly prickly foe. Beijing may not find it quite as easy to run roughshod over Hanoi in the coming years.

The lifting of the arms embargo also opens the door to other forms of U.S.-Vietnam security cooperation. A new arrangement for U.S. naval access to Cam Ranh Bay may well be in the offing. Hanoi will move cautiously and such access may be limited to the purposes of logistical support for the time being. But if China continues to play its cards wrong and if the United States proves itself a dependable partner, American warships could one day regularly operate out of Cam Ranh Bay, the strategically located port-of-call, for the first time since the Vietnam War.

Such access would complement the renewed U.S. presence in the Philippines; facilitate a regular American presence in the western part of the South China Sea; enable the United States to more easily defend—or seal up—the Malacca Strait; and, it should be noted, put American forces within striking distance of major Chinese bases on Hainan, including port facilities that host China’s ballistic missile submarines.

Less sexy but no less important is a forthcoming arrangement by which Vietnam will allow the United States military to preposition supplies and equipment in Da Nang on the central coast. Talks are focused on articles that are relevant to disaster relief, but the agreement’s eventual parameters could expand as the U.S.-Vietnam security relationship matures.

Should those ties continue to expand, moreover, the United States may find that it has greater flexibility in dealing with a vexing regional ally: Thailand. The U.S.-Thai relationship has suffered since the 2006 coup that overthrew Thaksin Shinawatra and especially since the latest coup, which saw the military take control in 2014 and stubbornly cling to power.

Thailand, of course, has been an important security partner for the United States. “The strategic value of the alliance remains high,” according to the Congressional Research Service:

*** “U.S. access to Thailand’s military facilities, particularly the strategically located and well-equipped Utapao airbase, is considered invaluable. Utapao has been suggested as a permanent Southeast Asian Humanitarian Assistance and Disaster Relief (HADR) hub. It can receive large aircraft (including C-17s and C-130s); it is close to a deep seaport; and it has infrastructure capable of handling command and control systems. The U.S. military used Utapao for refueling efforts during operations in Iraq and Afghanistan in the 2000s, as well as for multinational relief efforts after the 2004 Indian Ocean tsunami and April 2015 Nepal earthquake.”

The U.S.-Thai alliance has also served as a platform for important training exercises. The annual Cobra Gold exercise is Asia’s largest multilateral military exercise. Walter Lohman has described Cobra Gold as “an achievement that has proved useful for military missions, such as joint patrols of vital sea lanes, and noncombat missions, such as disaster relief following the 2004 Indian Ocean tsunami and the 2008 Cyclone Nargis in Burma.”

Unfortunately, the allies now lack a shared strategic outlook, thus reducing the impetus to overcome recent bilateral political hurdles. In particular, Thailand has a much more benign outlook on China’s rise and on its activities in the South China Sea, and although suggestions that Bangkok would dump Washington for Beijing are certainly overstated, Thai elites are hesitant to be drawn into what they see as a U.S. effort to contain the kingdom’s largest trade partner.

Ironically, the United States is drawing closer to communist Vietnam, in which human rights are serially abused, while growing apart from a major Vietnam War ally, largely due to concerns over democratic backsliding. Expanding U.S. access to Vietnamese facilities as described above could eventually render access to Thai facilities somewhat redundant, further weakening the institutional support for the alliance in the United States.

That redundancy will grant the United States flexibility in a couple of ways. First, the United States should feel more confident to pressure the junta on human rights concerns. Such pressure should focus on concrete, near-term objectives, such as putting a stop to “reeducation” of regime critics.

Second, the United States should feel comfortable adopting a patient approach in pushing a return to full democracy in Thailand. That should, of course, remain the goal, but Washington must recognize that Thailand is in the midst of a decade-long political crisis, which is unlikely to be resolved until after King Bhumibol’s passing and the royal succession is completed. Even then, the country’s division between royalists and red-shirts will likely endure. The Thai people are lurching towards a new political arrangement, a process that Thais have to see through for themselves. The United States needs to maintain a difficult balancing act, supporting the democratic aspirations of the Thai people while remaining a security and economic partner of choice for the elites and armed forces.

Thailand has little reason to jettison the alliance, but in the near term the United States may need to accept more distant ties and a closer Thai-Chinese relationship. Washington’s relationship with Hanoi will make that more palatable.

In practice, Thailand may be neutral in the region’s great power fissures into the next decade. And thus a new strategic map of Asia begins to emerge. It is one in which China dominates the South China Sea from the north; the United States and its partners dominate the eastern and western edges of the sea; and the bulk of continental Southeast Asian states (Thailand, Cambodia and Laos) are either neutral or aligned more closely with China.

Burma, however, is a potential bright spot for the U.S. position in continental Southeast Asia. Certainly, the ongoing reform process and the opening of relations with the United States amount to a strategic setback for China’s position in the region. With Burma internationally isolated for much of the past three decades, Beijing invested heavily in that country’s leadership. China sought access to natural resources, to political influence and to a strategic maritime position in the Bay of Bengal. Access to all three is now in doubt.

With the National League for Democracy now in power in Naypyidaw, China cannot rely on Burma as an automatic ally. Aung San Suu Kyi has no interest in antagonizing China—which shares a border with Burma and is a major source of foreign investment—but nor can she afford to alienate the United States or India. If full democratization is her goal, there is no foreign partner more important than Washington for achieving it.

China, of course, has important strengths in Burma. It has deep ties with the military, which still dominates key parts of the government, and is a major player in the economy. Beijing has also been careful to avoid estranging Aung San Suu Kyi and adopted a largely pragmatic approach to the country’s transition away from authoritarian rule. Despite all that, Beijing now faces a competition with Washington (and Delhi and Tokyo) for influence in Naypyidaw. How that competition will evolve remains to be seen, but the very fact of the contest should be understood as a reversal of fortune for China.

With a new Southeast Asian strategic alignment taking shape as described, geography makes Indonesia and Malaysia—especially due to its Sabah and Sarawak states on Borneo—the region’s key swing states. Should they be neutral, China may lord over the southern reaches of the South China Sea from military bases on its newly created and expanded islands in the Spratlys. Those bases may be vulnerable, but before and at the outbreak of hostilities, they will allow China to project power deep into maritime Southeast Asia, to threaten commercial and military passage through the sea, and to impose and enforce an air defense identification zone.

U.S. access to the military facilities on the South China Sea’s southern flank, however, would shift the region’s balance of power in America’s favor. Persistent American military presence at the eastern, southern and western points of the compass—especially when combined with regional states’ advancing ISR capabilities, for which the United States is providing investment—would enable the United States to respond rapidly to incidents in disputed island chains or to Chinese attacks on U.S. and allied naval and air assets or on commercial shipping. It would also open the option of persistently jamming Chinese radar installations in the Spratlys.

Chinese missiles on the mainland already hold all U.S. Asian bases at risk. Dispersed American forces would act as countermeasure and would complicate defense planning for the Chinese military and political calculations for Beijing, while ensuring U.S. forces are positioned to support each other in the event of a crisis.

Without the southern American presence, Chinese forces could more easily divide American forces east and west in the event of a crisis, more easily defend territorial claims or intimidate Malaysia and Indonesia, and more easily threaten maritime and air traffic crisscrossing the South China Sea.

All countries want positive economic and security ties with both China and the United States. Southeast Asians do not want to and should not have to choose between the two, but Chinese behavior is moving some states to pick sides—or at least to lean in one direction or another. When Beijing froze banana imports from the Philippines in the midst of the Scarborough Shoal standoff in 2012, it sent a clear message to its Southeast Asian neighbors: economic ties would not be immune from diplomatic contretemps. Indeed, when push came to shove, China would force its bilateral partners to choose between economic prosperity on the one hand and security and even sovereignty on the other.

It is little surprise, then, that Southeast Asian states are drawing closer to the United States—both seeking aid in developing their own defense capabilities and hoping that stronger ties act as a deterrent to Chinese assertiveness. But in order to achieve renewed stability in the region—to ensure that Southeast Asians are not susceptible to non-military Chinese coercion—the United States must strive to become more than just the security partner of choice.

When it comes to trade, investment and infrastructure development, China should not be the only game in town. Hence, the importance of the Trans-Pacific Partnership. Whomever is elected to be the next American president, that person would be wise to have in place a “Plan B” should the TPP fail to pass the Senate this year (such a Plan B is admittedly unlikely, given that both major candidates would bear responsibility for its failure in the first place).

The United States, moreover, should work with its other Pacific allies—Australia, South Korea and especially Japan—to consider ways that they can lead efforts to expand infrastructure investment in Southeast Asia, perhaps by reforming and enlarging the Asian Development Bank or by launching a joint infrastructure investment fund. The United States and its Pacific allies should consider whether it is feasible and sensible to coordinate the activities of USAID, the Japan Bank for International Cooperation (JBIC), the Korea International Cooperation Agency (KOICA), and Australia’s Department of Foreign Affairs and Trade.

Finally, the United States should prioritize governance issues in its relations with Southeast Asian states. Many of these countries suffer from corruption and lack for effective rule of law. Improved governance will lead to stronger economies over the long term and dampen the influence of Chinese dirty money. Tackling these issues will be tricky for the United States, as many of the elites that benefit from corruption will be those with whom Washington must work to deepen ties, but this is a long-term effort worth pursuing.

China is working hard to bring under its control the water, islands, rocks and reefs that sit within its imaginary nine-dash line. But as it does so, it acts as midwife to a very real strategic realignment in Southeast Asia, one which promises to benefit the United States and its partners. The United States can, if necessary, accept a continental Southeast Asia that “leans” China without major concern for America’s primary interests. The same cannot be said for China and a maritime Southeast Asia that aligns with the United States.

Importantly, the countries of maritime Southeast Asia are not aligning only with the United States, but with a grouping of external states concerned with the nature of China’s rise. It is growing more difficult to discuss Southeast Asia without discussing Japan, India and Australia, whose ties to the region and to each other are maturing and whose militaries—whether represented by personnel, aircraft, or warships—are increasingly present in the region.

Back in 2006, Japan became only the second country (after Russia) to establish a strategic partnership with Vietnam. The two countries elevated bilateral ties to an “extensive strategic partnership” in 2013 and Japan is in the midst of donating to Vietnam six patrol vessels (for use by the coast guard and fisheries ministry). Meanwhile, Japan is providing ten new multi-role vessels to the Philippine Coast Guard; Manila is also interested in procuring used P-3 Orion maritime patrol aircraft from Tokyo. Tokyo and Manila agreed to a strategic partnership in 2011.

India has likewise pursued deeper defense ties with Vietnam, and Indian warships just made port calls at Cam Ranh Bay and Subic Bay while en route to trilateral naval exercises with the United States and Japan in the Western Pacific. India is training crews for Vietnam’s new Kilo-class submarines and will sell Vietnam BrahMos supersonic cruise missiles. Narendra Modi’s “Act East” policy has resulted in an acceleration of burgeoning India-ASEAN ties and India’s position on the South China Sea territorial disputes essentially mirrors that of the United States. In a first, a Modi-Obama joint statement last year explicitly raised concerns over the South China Sea and called “on all parties to avoid the threat or use of force and pursue resolution of territorial and maritime disputes through all peaceful means.”

Australia, for its part, has vocally supported U.S. freedom of navigation exercises in the South China Sea and may have quietly conducted its own in recent months. In May, Australia and Singapore agreed to a “Comprehensive Strategic Partnership.” In the defense realm, the CSP paves the way for more bilateral military exercises, greater Singaporean access to Australian training facilities, enhanced intelligence-sharing arrangements and expanded people-to-people exchanges. In April, Australian Defence Force personnel joined the U.S.-Philippines Balikatan maneuvers, which included an amphibious landing exercise. Australia and Vietnam established a “Comprehensive Partnership” in 2009 and agreed to expand it in 2015. Hanoi and Canberra have launched a number of security dialogues and are expanding personnel exchanges, ship visits and officer training.

The United States now has the opportunity to secure for another generation the peace that has held in Asia for nearly four decades now. The Obama administration has made modest gains in this regard, but it will be up for to the next president to seize that opportunity and ensure that Southeast Asia’s future is prosperous, peaceful and free.

Michael Mazza is a research fellow in foreign and defense policy studies at the American Enterprise Institute (AEI). You can follow him on Twitter: @Mike_Mazza.