In the face of Russia’s recent nuclear saber rattling in the Russo-Ukrainian war and North Korea’s adoption of a more aggressive nuclear policy, the credibility of U.S. extended nuclear deterrence has become the core issue of its non-nuclear allies’ security strategy. This article delves into their credibility management actions by drawing on analyses of European NATO allies and South Korea. Active engagement in the risk sharing and responsibilities of the alliance’s nuclear deterrence posture enables higher-level management of the credibility of U.S. extended nuclear deterrence. To that end, European NATO allies with forward-deployed U.S. nuclear weapons have facilitated the broadest possible engagement in NATO’s nuclear deterrence posture through the annual Steadfast Noon nuclear deterrence training exercise and policy consultation on nuclear issues via the Nuclear Planning Group (NPG). In contrast, South Korea’s credibility management has been limited due to its low level of engagement in the US-ROK nuclear deterrence posture. This article assesses the applicability of importing NATO’s present-day concept of nuclear sharing to South Korea and proposes measures for strengthening South Korea’s confidence in U.S. extended nuclear deterrence from the recipient’s perspective.