The US debate on NATO nuclear deterrence since 1991 has been a barely visible and sometimes entirely behind-the-scenes contest between the traditional view, which is supportive of longstanding US and NATO policy, and the diverse views of various proponents of change. The principle of maintaining a credible NATO nuclear deterrence posture has continued to command widespread support. Most of the current controversy concerns how to maintain such a posture and, above all, whether nuclear risk-and responsibility-sharing arrangements involving US nuclear weapons in Europe should be sustained. These nuclear risk-and responsibility-sharing arrangements began in the late 1950s, and some US weapons must be retained in Europe if this sharing is to continue in the form in which it was then established and has since been developed.Owing to the longstanding importance of nuclear risk-and responsibilitysharing, different views on the future of the US nuclear weapons presence in Europe have come to represent different broader positions. Some Americans have come to see maintaining US nuclear weapons in Europe as irrelevant and counterproductive, in the light of their judgements as to deterrence and assurance requirements, while others have seen continuing utility in nuclear risk-and responsibility-sharing and associated arrangements. The US nuclear weapons in Europe have, in other words, been perceived through different analytical lenses. The prudence of sustaining-or unilaterally removing, without any Russian reciprocity-the remaining US nuclear weapons in Europe has therefore become one of the key issues in dispute. The somewhat artificial focus on US nuclear weapons in Europe has persisted, despite the fact that there are other important issues related to US extended deterrence. The extension by Washington of a credible umbrella of deterrence protection also depends on US intercontinental forces, missile defences, non-nuclear capabilities, declaratory policy, strategic targeting policy, and relations with the NATO allies, among other factors. * The views expressed are the author's alone and do not represent those of the Department of the Navy or any US government agency. The author presented an earlier version of this article at a conference entitled 'The future of NATO deterrence policy', organized by the Fondation pour la recherche stratégique, Paris, on 26 May 2011. Thanks are owed to those who commented on drafts of this article, including