‘Nuclearization’ of the U.S.-Japan Alliance: Its Evolution and Implication

Abstract

Since the Crimea crisis in 2014, the international nuclear order bed-rocked on the Nuclear Non-Proliferation Treaty (NPT) has become severely distressed due to lack of cooperation among nuclear stakeholders. Especially, stalling disarmament dialogue between the United States and Russia amplifies such a negative atmosphere. To be worse, the competitive nuclear-weapon powers have been beefing up their nuclear capability and sharpening their nuclear doctrines in recent years.

The demise of the Anti-Ballistic Missile (ABM) Treaty in 2002 and the expiration of the Intermediate-Range Forces (INF) Treaty in 2019 have undermined the “strategic stability” which was established and maintained by the US and the Soviet Union, later Russia, through a series of nuclear arms-control negotiations during the Cold War.

Behind these destabilizing scenes played by the former super-powers, China, another nuclear rising power, has steadily increased her strategic capability through deployment of new nuclear missiles and hypersonic weapons for the past decade. North Korea is another big nuclear challenge against regional stakeholders like Japan, South Korea and the U.S. that promises to provide strategic deterrence in East Asia.

Giving a rough overview of the recent nuclear landscape shaped by these strategic trends, this paper mainly analyzes evolutions of the U.S.-Japan alliance influenced by U.S. nuclear policy, especially represented by each administrations’ Nuclear Posture Review (NPR), and deteriorating security situation in East Asia.

For example, the Trump administration announced its own NPR in 2018 and broadened nuclear retaliation option against “non-nuclear strategic attack” which may include adversary’s cyber-attack on the U.S. nuclear command and control system. At almost the same timing of an announcement of Trump NPR, the Japanese Abe administration expressed a high evaluation of the NPR, because Japan strongly desired to strengthen the U.S. extended nuclear deterrence against the backdrop of on-going military crisis provoked by North Korea’s nuclear and missile tests.

Based on exclusive interviews with current and former officials of the U.S. and Japan, the paper focuses on diplomatic process of the two allies for solidifying the nature of “nuclear alliance” through the Extended Deterrence Dialogue that started under the Obama administration in 2010. Differently from NATO, the U.S.-Japan alliance has not ever formalized any mechanism to share and operate U.S. nuclear weapons at the time of contingency. However, the paper sheds a light on how the U.S. and Japan have evolved their nuclear bond particularly for the past decade.