Uncertainty in U.S. Nuclear Extended Deterrence and the Rise of Complementary Nuclear Deterrence

초록

The credibility of U.S. nuclear extended deterrence has come under increasing pressure amid the deterioration of the global nuclear order, intensifying strategic competition, and the weakening of nuclear arms control. These concerns have been reinforced by the second Trump administration’s aggressive foreign policy based on “America First” approach. The U.S. government’s rhetoric and actions have increased uncertainty about the future reliability of the U.S. nuclear umbrella. This article examines whether such uncertainty is encouraging allies and partners to pursue complementary nuclear deterrence arrangements and how these arrangements differ from the existing U.S.-provided system. It first conceptualizes the credibility of nuclear extended deterrence. It then examines emerging cases, including France’s expanding nuclear role in Europe and Saudi Arabia-Pakistan security cooperation. The article argues that these developments do not necessarily indicate an attempt to replace the U.S. nuclear umbrella. Rather, they represent efforts to supplement and reinforce specific functions of U.S. nuclear extended deterrence in response to growing uncertainty about its credibility. The article concludes by assessing the implications of this emerging trend for U.S-South Korea nuclear extended deterrence and the future regional nuclear order.

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