In recent weeks, U.S. allies have experienced two seismic shifts. While still on Chinese soil, U.S. President Donald Trump announced that he was considering holding up a $14 billion arms sales package to Taiwan of vital defense articles that Congress had already authorized. Separately, without substantial consultations with Congress or European allies, the Trump administration announced, backtracked on, and then pressed ahead with plans to reduce U.S. assets assigned to Europe.
Together, these actions raise questions about Washington’s willingness to sell arms and deploy troops, the two most critical ways that the United States has historically backstopped its allies and partners.
European and Asian allies both expressed concern about these developments, but their reactions to Washington’s policies have diverged over the last year. NATO allies have pulled more closely together in the face of U.S. threats to abandon their security through vehicles such as the coalition of the willing that supports a multilateral force in Ukraine. They have begun to form a backup plan through bilateral pacts with one another, as in the case of Britain and Germany and Britain and France, and launched the SAFE mechanism to support European defense manufacturing. All of these are intended to build resilience in case the United States continues to rethink its commitment to trans-Atlantic cooperation.
Of course, this Plan B could not fully compensate for a U.S. pullback, but it could minimize the damage, particularly if the United States provides sufficient time for an orderly transition as European allies to step up.
America’s Asian allies, on the other hand, have no such Plan B. Throughout the second Trump administration, they have been steady in standing against tariffs and resolved to spend more on defense. Yet when asked how they would guard against U.S. threats to withdraw troops or suspend defense sales, their answers have been clear and consistent: There is no Plan B. For Australia, Japan, the Philippines, and South Korea, the alliance with the United States cannot be replaced.
The source of this resignation is not mysterious. Without multilateral structures like NATO and the European Union, Asian allies do not have the collective security or economic integration mechanisms that could compensate for U.S. support. Instead, they are still deeply reliant on a hub-and-spokes system centered on the United States. Furthermore, whereas NATO’s European members have a 9-to-1 combined advantage in total GDP over Russia, America’s Asian allies have a 3-to-1 disadvantage in GDP to China (1.5-to-1 if Taiwan and India are included). Any U.S. pullback would leave Asian allies with deficits in both coordination and scale.
Addressing Asia’s coordination and scale constraints has heretofore been viewed as too hard or even impossible. The aftermath of the recent summit between Trump and Chinese President Xi Jinping, however, should spur efforts to address these gaps more seriously. Although the summit produced few deliverables, the optics of Trump courting a confident Xi raised concerns among Asian allies. But the real alliance warning shots came after the meeting, when Trump openly mused about withholding arms sales to Taiwan at Beijing’s request. In doing so, he opened the door for arguably the biggest change in U.S. cross-strait policy in decades.
As Trump unspooled the logic of reconsidering arms sales to Taiwan, his justification sounded remarkably like that of Xi himself. Trump asserted that U.S. policy toward Taiwan was old and outmoded, that Taiwan was far from the United States and close to China, and that Taiwanese President Lai Ching-te was a pro-independence troublemaker who could entangle Washington in a conflict. In a leader-level conversation that was the culmination of a year’s worth of diplomatic energies, Xi appeared to have upended more than 40 years of bipartisan U.S. policy. To be sure, the U.S. president changes his mind frequently and parrots the words of others. But even contemplating this should send shockwaves through allied capitals in Asia.
What’s more, Trump’s remarks already seem to indicate a broader shift: At the Shangri-La defense dialogue in Singapore later in May, U.S. Defense Secretary Pete Hegseth did not mention Taiwan; instead, his speech laid out a new approach to China that eschews “needless confrontation” and endorsed a “quiet” approach, in a stark departure from his 2025 comments before the same audience.
The possibility of delayed or downsizing U.S. arms sales is a military risk for Taipei, which depends on U.S. defense equipment to deter and defend against Beijing—and can count on no other partner. Politically, it is just as significant, since it could undermine Lai and his Democratic Progressive Party’s efforts to boost Taiwan’s defense spending. Ironically, this defense spending uplift came in part at the behest of the Trump administration.
China will use this development in its long-standing disinformation campaigns in Taiwan, where it will amp up messing that the United States is not a reliable partner and that the current status quo is therefore untenable.
Trump’s comments will also loom large in other capitals across the region. Putting arms sales on the negotiating table with China suggests that the United States could rethink support for treaty allies, too. If the United States is willing to treat a key partner as a bargaining chip with Beijing, then an ally’s security could also be up for grabs at the right price. What’s more, Trump’s embrace of the concept of “comprehensive strategic stability” and of a warm personal relationship with Xi raises the basic question of whom the United States stands with and what it stands against.
If Washington and its closest allies do not share threat perceptions and diverge in their views of the need to defend Taiwan, the basic logic of many of these pacts begins to dissolve. Decades of international relations scholarship reminds us that alliances form and persist in the face of a common adversary, and while it is possible for them to limp along without a shared threat (such as much of the U.S. alliance system after the Cold War), this would be untenable in a world in which China continues to pose real threats to Australia, Japan, and the Philippines.
To make matters worse, the U.S. Defense Department’s on-again, off-again decisions to withdraw forces and platforms from Europe will spike agita in Seoul, which has worried about a similarly drawdown from the Korean Peninsula. While much remains unclear about each of these developments, one thing is certain: U.S. allies in Asia can no longer hope for the best from Washington. They are out of time to build a Plan B.
With a new and jarring picture of U.S. priorities in Asia, allies must act to preserve their long-standing security interests, particularly vis-à-vis China. Their action plans should each have two lines of effort: 1) boosting their own domestic defense and intelligence capabilities and 2) linking themselves more closely to one another and to European partners. Only by doing so can these countries start to fill the gaps that would be left by the loss of U.S. coordination and scale.
The first step in compensating for the risk that Washington might downgrade its support is for Asian allies to increase their own defense capabilities. This is already occurring, but Asian leaders should accelerate these efforts in the months ahead.
Several factors should aid their efforts. First, growing fears about U.S. abandonment are likely to enable increased appetite for defense spending in some capitals. Second, Washington’s notifications that some allies will see their arms sales delivery timelines slip as a result of the Iran war could accelerate a desire for indigenous production. There is a risk, however, that this could lead to a more fractured and less interoperable set of allied capabilities.
The only antidote is for Australia, Japan, the Philippines, South Korea, and others (particularly India) to rapidly start co-developing and co-producing key systems. Japan’s recent policy shift to allow export of defense equipment has opened the aperture for major cooperative efforts, such as Australia’s acquisition of the Mogami-class frigate. As defense spending spigots open in the years ahead, they should feed into regional co-development and co-production efforts. This is the only way to build the scale necessary to provide for a potential Plan B.
Indo-Pacific allies must also accelerate efforts they started alongside the United States to better pool their capability and capacity through strategic networking. Through minilaterals such as the Quad, the Japan-South Korea-U.S. trilateral, AUKUS, and the Squad (Australia, Japan, the Philippines, and the United States), the Biden administration started and the Trump administration has preserved numerous new joint exercises, intelligence-sharing initiatives, and technology-sharing arrangements, all of which have boosted these countries’ capacities to work together.
They should not wait for a distracted Washington to take the next steps forward but should accelerate them themselves, welcoming U.S. participation when offered and accepting its absence when unavoidable. Japanese Prime Minister Sanae Takaichi and South Korean President Lee Jae-myung’s continued commitment to Japanese-Korean rapprochement shows that these allies understand they need each other. But in the face of a U.S. administration as unpredictable as this one, they must speed their joint exercises, information sharing, defense procurement, and cooperative planning as a backstop against abandonment. By doing so, they can address the coordination gaps left by a damaged hub amid their spokes.
Finally, given the power disparities involved, addressing Asian allies’ scale deficit requires a broad coalition beyond the region itself. As Europe steps up, there is an opportunity for European and Asian countries to deepen industrial cooperation. South Korea has already been ramping up sales to European partners in recent years, which highlights the benefits of Europe and Asia sharing technological expertise and manufacturing know-how.
In the past, the United States has served as a bridge between Europe and Asia. Key regional players should now take on these roles themselves. Existing bilateral defense industrial cooperation between Japan and Britain and Italy, France and India, South Korea and Poland (as well as Canada), and others could serve as linkages to build on. A set of multilateral dialogues between leading European and Asian powers could extend these nascent efforts and serve as a parallel track to groups such as the G-7, which have become increasingly fraught in recent years.
Even if U.S. allies in Asia take each of these steps with enthusiasm, their efforts will not soon replace the long-standing role of the United States. Nevertheless, these initiatives will help insulate their interests from Chinese opportunism and will send signals to Beijing that U.S. unpredictability will not tilt the region ineluctably toward China.
They will also buy time for the United States to return to a foreign policy that prioritizes the maintenance of stability through the use of alliances in both regions. What’s more, if these efforts make headway, allies will be building resilience for an era of volatile U.S. domestic politics and leave all partners better positioned for a future in which Washington may become unpredictable again.
The era of unquestioned reliance on Washington ended in Europe some time ago; it may be reaching its finale in Asia, too. U.S. allies must now prepare for a future in which they still work closely with Washington but are increasingly dependent on themselves—and one another—to maintain security.
