Since the collapse of the Soviet Union, the need to reassure allies has become, perhaps by default, one of the more important rationales for continuity in U.S. nuclear posture. In fact, a view frequently expressed by current and former U.S. officials holds that Washington still maintains the largest strategic nuclear arsenal in the world precisely to provide these assurances.

Since the collapse of the Soviet Union, the need to reassure allies has become, perhaps by default, one of the more important rationales for continuity in U.S. nuclear posture. In fact, a view frequently expressed by current and former U.S. officials holds that Washington still maintains the largest strategic nuclear arsenal in the world precisely to provide these assurances.

Most recently, a report from the Strategic Posture Commission took this idea in a somewhat different direction. It maintained that “extended deterrence,” i.e., nuclear deterrence on behalf of allies, is needed to inhibit the further proliferation of nuclear weapons. For at least some allies, including Japan, the report connected this outcome to the continued presence of U.S. tactical nuclear weapons.

Does the assurance of allies and the prevention of nuclear proliferation really depend on specific and identifiable numbers or locations of nuclear weapons? There is little reason to think so.”

But are these claims reasonable and well-supported?

As if on cue, events have conspired to undermine this portion of the report. In January, a letter from Japanese Foreign Minister Katsuya Okada to Secretary of State Hillary Clinton was made public that disavowed any specific stance on U.S. tactical nuclear weapons. According to a translation by the Citizens’ Nuclear Information Center, Okada stated that Japan was “not in a position to judge whether it is necessary or desirable” for the United States to retain particular weapons systems, including the nuclear Tomahawk cruise missile, or TLAM-N, which the commission’s report had deemed to be of special importance to Tokyo.

Shortly thereafter, Japan’s new government went a step further by breaking with the opacity that long surrounded U.S. nuclear weapons in and around Japan. The government openly acknowledged once-secret understandings that allowed Washington to bring nuclear-armed vessels into Japanese ports without notice. Although U.S. Navy boats haven’t carried nuclear weapons for almost two decades, this disclosure symbolically closes the books on tactical nuclear weapons in Japan. There is certainly no indication that Tokyo will now seek its own nuclear arsenal; if anything, its commitment to abstention has been reaffirmed.

Events in Europe, where a few hundred U.S. nuclear gravity bombs remain deployed at certain NATO bases, are now moving haltingly in the same direction. In late October, a new governing coalition in Germany produced a policy statement [in German] expressing concern about the state of the arms control and nonproliferation regimes and pledging to contribute to President Barack Obama’s vision of nuclear disarmament. In a translation by the Acronym Institute, the coalition agreement promised to “advocate within NATO and towards our U.S. allies a withdrawal of remaining nuclear weapons from Germany.”

Washington sounded a cautionary note in response. Clinton reminded Germans in an early November interview that “we have obligations to states further east. We have obligations to states in the Balkans and further south. So we have to bring everyone’s opinion to the table as we consider what to do.”

These remarks only hinted at the nature of Washington’s concerns about removing tactical nuclear weapons. More recently, however, three former U.S. and British officials accused the Germans of opening a “Pandora’s box,” warning bluntly that revisiting NATO’s “nuclear-sharing” arrangements could jeopardize Turkey’s commitment to nuclear nonproliferation. The progress of Iran’s nuclear programs, they argue, creates pressure to acquire nuclear weapons that extends even to a NATO member state, i.e., Turkey.

Undeterred, the foreign ministers of Belgium, Germany, Luxembourg, the Netherlands, and Norway have now asked NATO Secretary-General Anders Fogh Rasmussen to place a “comprehensive discussion” of nuclear arms control, nonproliferation, and disarmament on the agenda of an upcoming NATO meeting in Estonia. Meanwhile, the public debate over the future of NATO’s nuclear weapons has effectively already begun, stirred by peace activists’ repeated intrusions onto a poorly secured air base in Belgium.

While the case of NATO remains unsettled, let’s take a moment to ask the larger question: Does the assurance of allies and the prevention of nuclear proliferation really depend on specific and identifiable numbers or locations of nuclear weapons, especially tactical nuclear weapons? There is little reason to think so. Neither the capabilities nor the will of the United States to defend its treaty allies can be seriously questioned. Washington has led coalitions into large-scale armed conflict abroad four times since the end of the Cold War–to liberate Kuwait, to defend Kosovo, to drive the Taliban from power, and to unseat Saddam Hussein. Our willingness to pay in blood and treasure for interests and causes around the world has no parallel.

In addition, our commitment to allies is expressed in a variety of lesser, more ordinary ways, from trade and diplomatic relations, to bilateral and multilateral institutions and consultations, to arms sales and training, to joint military exercises and basing arrangements. Especially in the absence of the Soviet threat, these measures seem more than sufficient. After all, beyond the Middle East and the Korean Peninsula, few, if any, U.S. allies face anything resembling the sorts of dangers that spurred the Cold War nuclear buildup.

Even in those dark days, the details of extended deterrence were less of a consideration in preventing nuclear proliferation than is now advertised; they were certainly less important than the basic question of willingness to accept dependence upon a superpower ally. How else can we explain the British and French choices to acquire nuclear weapons in the 1940s and 1950s, despite massive U.S. nuclear superiority? By contrast, West Germany, Italy, and Japan, among others, remained satisfied with extended deterrence for the duration of the Cold War.

Today, the lack of a traditional nuclear threat to most of our allies is telling. The debate in Britain over whether to replace the Trident submarine-launched ballistic missile centers on cost concerns. If Turkey should ever decide to build a Bomb, how Ankara’s leaders judge the status of Iran’s nuclear program and whether they believe the country ought to “stand on its own two feet” will loom larger than the locations of U.S. nuclear weapons.

Defense officials have long struggled with how to translate weapon systems into deterrence, whether extended or “central.” How to translate weapons into nonproliferation is murkier still. Just one thing is clear: Today’s nuclear threats center on the possible unraveling of the nonproliferation regime and the risk of nuclear terrorism. That inspires questions about the continued relevance of nuclear policies and postures originally devised with the Soviet Union in mind. The need to reassure U.S. allies doesn’t prevent us from revisiting the basing of tactical nuclear weapons, and it shouldn’t.