Abstract

 “Let me reiterate that our treaty commitment to Japan’s security is absolute,” declared President Barack Obama in Tokyo in April 2014. “Article 5 covers all territories under Japan’s administration, including the Senkaku Islands,” he continued, referring to the part of the alliance whereby the United States promises to provide military aid to Japan if it is attacked.¹ Days later, the President announced a new basing agreement in Manila, affirming Washington’s commitment to help “build the Philippines’ defense capabilities,” calling it a “vital partner” in maritime security.² These two presidential statements underscore an increasingly salient set of regional policy quandaries. Maritime and territorial disputes in the Pacific have become prominent in recent years and, when U.S. allies are involved, they present a unique challenge to extended deterrence in the region—one with which Washington is only beginning to grapple.

Although it has relied on extended deterrence since the early Cold War, the United States’ so-called “nuclear umbrella” is predominantly designed to deter nuclear and major conventional attacks against the sovereignty and territory of treaty allies. This may, however, have little role to play in deterring conflicts around offshore disputed territories. In recent years, Washington has faced mounting assurance and deterrence challenges because some of its close treaty allies in the Pacific are involved in territorial and maritime disputes, which frequently pit them against a rising China. Rather than fixate on the massive conventional invasions or nuclear attacks that preoccupied U.S. allies during the Cold War, some U.S. allies presently worry that they will not have support if they become involved in a less-than-existential conflict over a disputed island territory or a maritime boundary.

There are at least three reasons why these conflicts present a challenge to U.S. extended deterrence as it has traditionally been practiced. First, existing U.S. treaty commitments themselves do not provide much guidance to adversaries or allies on whether Washington would intervene in a territorial dispute on behalf of an ally, and if it would, under what conditions. Second, where uninhabited islands, rocks, or shoals are at issue, U.S. allies necessarily have a far greater stake in the dispute than the United States itself, making it more difficult for Washington to make its defensive commitments credible. Third, unlike in the Cold War standoff between the United States and Soviet Union, the United States and China are not sworn adversaries. Given its ample incentives to find a modus vivendi with Beijing in other areas, Washington maintains a position of neutrality on most maritime and territorial disputes and does not overtly back its allies’ sovereignty claims. China is, however, rising rapidly, and may therefore have both the capability and the will to press its claims against U.S. partners, even as Washington avoids taking sides. Taken together, these challenges combine to mean that allies’ fear of abandonment may run especially high when it comes to U.S. alliance commitments around lower- level disputes.

This article proceeds with a brief overview of extended deterrence and assurance in U.S. foreign policy, defining these terms and discussing their role in Cold War strategy. I argue that 21st-century East Asia presents a novel extended deterrence context for the three reasons mentioned above, illustrating why U.S. allies’ abandonment fears run especially high with the examples of the Senkaku/ Diaoyu Islands and the U.S.–Japan alliance as well as the Philippines’ Spratly Islands claims in the U.S.–Philippines pact. I argue that it is in Washington’s interest to address these abandonment fears and remain a committed alliance partner in this new extended deterrence context, recommending a few measures it can take to assuage allies’ anxieties while maintaining a working relationship with Beijing.

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