Exclusive Interview
Against the backdrop of a changing military-political environment in Northeast Asia, issues of U.S. extended deterrence are becoming increasingly relevant. The development of China’s nuclear capabilities, as well as the situation surrounding North Korea’s missile and nuclear program, are drawing heightened attention from Washington’s key allies – Japan and the Republic of Korea. In this context, assessing the current state of U.S. security guarantees and the prospects for the evolution of the regional deterrence architecture is of particular interest.
PIR Center conducted a series of interviews with leading international experts on strategic stability and arms control.
One of our interviewees was Dr. David Santoro, President and CEO of the Pacific Forum.
The interview was conducted by Mr. Ilya Subbotin, PIR Center intern.
Mr. Ilya Subbotin: Dr. Santoro, how would you characterize the current dynamics of U.S. extended deterrence in Northeast Asia, specifically regarding Japan and South Korea? What are the main challenges and trends today?
Dr. David Santoro: I would say that the situation is very dynamic and evolving rapidly. When discussing this issue in the broader region – the Indo-Pacific, one might also mention countries such as the Philippines and Australia, but in the context of Northeast Asia, the focus is clearly on Japan and South Korea.
Both countries are increasingly concerned, particularly because they observe China expanding and modernizing its nuclear arsenal. As a result, they believe they must not only improve their own approaches to defense and deterrence but also rely on the United States for the ultimate security guarantee, which, of course, involves nuclear weapons. Extended deterrence is not exclusively about nuclear weapons, but they constitute a significant component of it.
Essentially, Japan and South Korea want to be certain that the United States will stand by them in the event of a crisis. One concern they had was that the U.S. National Security Strategy released at the end of last year did not explicitly mention extended deterrence. This caused some anxiety, particularly because these countries are trying to encourage the United States to do more in this area. If extended deterrence is not clearly part of the strategic framework, that could be problematic. However, soon after the document’s release, U.S. officials reassured them that the American nuclear guarantee remains in place.
Mr. Ilya Subbotin: Are there any prospects for trilateral nuclear integration between Washington, Seoul, and Tokyo? In other words, is an Asian model of bilateral or multilateral nuclear sharing – similar to NATO – feasible or currently envisioned in the United States?
Dr. David Santoro: The short answer is no. For many years, the United States has tried to encourage security cooperation between Seoul and Tokyo, including coordination in defense and deterrence. However, the focus has always been on coordinating the two bilateral alliances – U.S.-Japan and U.S.-South Korea – rather than transforming Northeast Asia into something resembling a small NATO or establishing a nuclear-sharing arrangement. The emphasis is on coordination, not integration, and not focused on nuclear weapons.
Mr. Ilya Subbotin: However, in 2023, the Camp David Declaration was adopted by the leaders of the United States, South Korea, and Japan. Could this be interpreted as a sign of the emergence of a trilateral alliance, possibly even one with a nuclear dimension?
Dr. David Santoro: It represents trilateral coordination, yes, but not a trilateral alliance. The political contexts in South Korea and Japan are quite different, which makes the formation of a formal alliance unlikely. What we will likely see instead is improved coordination rather than a formalized alliance structure.
Mr. Ilya Subbotin: Do you think the U.S. nuclear umbrella over South Korea and Japan is sufficiently credible? Is Washington truly prepared, as the question is often phrased, to sacrifice Seattle or Washington for Seoul or Tokyo? More broadly, when the U.S. could consider the use of nuclear weapons in a crisis to defend its allies?
Dr. David Santoro: That question is extremely difficult to answer, both in the Asian context and in Europe. The issue has always been the same: in the event of a crisis, conflict, or war, would the United States actually honor its commitment and employ extended deterrence against an adversary?
The truth is that you cannot know until such a situation actually arises. What I can say is that for many years, the United States has been strengthening extended deterrence in both Asia and Europe. If anything, Washington has been doing more to reassure its allies that it would act in their defense if necessary. Ultimately, however, the decision to use nuclear weapons rests with the President of the United States. No matter how much extended deterrence is strengthened, the actual decision in a crisis will depend on the specific context and the president’s judgment at that moment.
And I would not say that U.S. nuclear umbrella is a myth. It is a real policy instrument and a genuine commitment. It could be implemented, if necessary, although it could also fail. In other words, it is not merely symbolic; it is real, but there is always the possibility that it might not function as intended.
Mr. Ilya Subbotin: Why, then, is Washington so committed to strengthening extended deterrence? Beyond deterring China and North Korea, are there other considerations, such as maintaining the credibility of U.S. global alliance system as a whole?
Dr. David Santoro: There are probably two main reasons. The first is to strengthen deterrence itself. By reinforcing extended deterrence, the United States strengthens defense and pushes back against potential adversaries.
The second reason is the reassurance of allies. The prevailing view in Washington is that if the United States does not reassure its allies that it will protect them, those allies may take matters into their own hands. Many today discuss the possibility that South Korea might develop its own nuclear weapons. The concern in Washington is that if extended deterrence is not sufficiently strong, countries like South Korea and others might consider acquiring their own nuclear capabilities, something the United States does not want to see.
Mr. Ilya Subbotin: In the short and medium term, how likely is it that South Korea or Japan could develop their own nuclear arsenals, or at least host U.S. nuclear weapons on their territory? And would the United States support such a scenario?
Dr. David Santoro: Over time, the likelihood has certainly increased. Ten years ago, it was less likely than it is today. Nevertheless, I still believe that it remains unlikely. Both South Korea and Japan are signatories to the Nuclear Non-Proliferation Treaty (NPT), and developing their own nuclear weapons would require violating international law. That makes such a step very difficult.
That said, the regional security environment has deteriorated significantly, which makes the possibility of creating indigenous nuclear weapons by Seoul or Tokyo somewhat more plausible today than it was a decade ago.
It is probably more likely that the United States would agree to deploy tactical nuclear weapons on the Korean Peninsula than that it would allow South Korea to develop its own nuclear arsenal. Even so, I still consider the deployment of U.S. tactical nuclear weapons in Korea to be unlikely. It is not impossible, but it is unlikely. The development of independent nuclear weapons by Japan is even less likely.
Mr. Ilya Subbotin: Regarding Washington’s nonproliferation policy, last autumn an article in Foreign Affairs argued that “selective proliferation” among U.S. allies might be beneficial. Do you think this represents only the views of individual experts, rather than a shift in U.S. policy?
Dr. David Santoro: The discussion of so-called “friendly proliferation” has been part of policy debates for many years. There have always been commentators who argue that it might be beneficial for allied countries to develop their own nuclear weapons. However, this is not official U.S. policy, and the United States has not changed that policy.
The United States still prefers its allies not to acquire nuclear weapons.
For example, the current U.S. administration has been urging European allies to increase their defense spending and take greater responsibility for their own conventional defense. The implication is that while Europe should manage its conventional security more independently, the U.S. nuclear guarantee remains in place.
Similarly, in Asia, there is no interest in allowing countries like South Korea to develop their own nuclear weapons. Therefore, I do not believe that “friendly proliferation” represents an actual policy direction.
Keywords: Nuclear nonproliferation; United States; Japan; Republic of Korea
NPT
E16/SHAH – 26/03/18
