Understanding Doubts Over U.S. Extended Nuclear Deterrence in Asia

The tenuous logic of trading Seattle for Seoul is being further tested by Trump administration.

While nebulous and difficult to measure, credibility is a key component of functioning alliances. An ally must be viewed as having both resolve and capacity to fulfil their commitments. This is especially important for “junior” alliance partners.

The difficulty with the Trump administration is that possibilities that once seemed remote are now on the table and must be factored into the security calculations of friends and foes alike. Tariffs imposed then put on pause are only one example of the credibility question. The possible demise of NATO’s collective defence commitments is another. Through NATO, the United States provides “extended deterrence” to its allies in Europe by maintaining a nuclear umbrella that included its members. Moves to explore a French option to extend nuclear coverage underscore the nagging doubts about U.S. credibility.

A key question for Asian allies and partners is whether dynamics will be transferrable from Europe to Asia, and what this might mean for the future of extended deterrence. Should Asian partners be worried?

There is a belief among some quarters that the Trump administration wants to strike a peace deal over the conflict in Ukraine so it can turn its attention to the main game: China. That tariffs now specifically target China might support this argument.

In Washington, there remains a general bipartisanship that China is the main competition. A revealing early priority is the focus on naval and commercial shipbuilding to compete with China’s growing maritime capabilities.

There is also an argument that the MAGA crowd have a particular disdain for Europe that does not extend to allies in Asia.

Defence Secretary Pete Hegseth’s emphasis on the theme of “peace through strength” in the Indo-Pacific provided some comfort, as the focus on deterrence and partnerships was similar to what one might have expected from the Biden administration.

Nevertheless, Asian allies may not be reassured and instead hear the louder invocation of “America first”. After all, it is not only Europe that has been torched by U.S. hostility. Canada is also the target of economic tariffs and bombastic “51st state” rhetoric. This had such an effect on public opinion in Canada that the Liberal Party’s pushback against the Trump administration might see it secure a dramatic and unexpected victory in the forthcoming election.

It is hard to imagine that any U.S. ally will think that they are immune. Cuts to USAID as well as support for Voice of America and Radio Free Asia will reduce U.S. influence and credibility across the region, leaving space for China to present itself as a responsible and trustworthy actor.

Part of the challenge is we don’t really know what Trump’s Asia security policy is yet.

And the wildcard is Trump himself. He seems primarily concerned with the optics of being a “dealmaker”. Trump might not trust Xi Jinping, but if “dealmaking” is the point then there is a possibility that the U.S. and China might come to an arrangement that could affect the broader security landscape of East Asia.

A publicly released photo by the U.S. military of the re-entry of an unarmed Minuteman III inter-continental ballistic missile over Marshall Islands (U.S. Army Space and Missile Defence Command)

Economics cannot be bracketed from security – if the U.S. looks like a less trustworthy economic partner, this is likely to bleed into how allies and partner view its credibility as a security partner as well. If Japan and South Korea, or even Taiwan, no longer feel that the U.S. nuclear umbrella extends to their defence, what effect will this have on their nuclear policies?

In South Korea, for example, domestic debates about obtaining a nuclear option have only intensified in the early days of the Trump administration even amid the local political turmoil. Japan is also assumed to have a “latent nuclear weapons capability”.

Support for U.S. extended deterrence helped contain the global proliferation of nuclear weapons. Should the credibility of this umbrella be fraying in the region, policymakers and the public alike should be alarmed.

Australia has previously been an important advocate against nuclear weapon proliferation. A key question in preparing for an increasingly uncertain future is how Australia can continue to work with regional partners to prevent proliferation as part of a broader conflict prevention agenda.

Dr. Bec Strating is Director of La Trobe Asia and Associate Professor of Politics and International Relations at La Trobe University, focusing primarily on maritime disputes and Australian foreign policy.

This article appeared originally at Lowy Institute's the interpreter.