The Pentagon may be able to make sound arguments for developing a new generation of smaller nuclear weapons, as recommended in a congressionally requested report, the Nuclear Posture Review. But for the last half-century, nuclear bombs have been strictly a political tool and a means for avoiding rather than engaging in war. If the Bush administration’s goal is “enhanced deterrence,” as it states in the report, it needs to explain why technology that broadens the use of nuclear weapons at the same time makes their use less likely.

The new weapons, described in a June 2000 paper by Stephen M. Younger, now of the Pentagon, might be able to penetrate deep underground without causing extensive damage to surrounding areas. They are described as producing more a tunnel than a pit to place a nuclear device in a deep bunker. It is an idea – and it is important to note that it has yet to be developed – that has special appeal as U.S. troops battle al-Qaida in the Afghan hills. But it has understandably worried allies, who see in the weapon’s chief characteristic, its limited destructive power, the greatest temptation for use.

The American nuclear weapons programs began as a race against Germany and the Soviet Union, and while the United States dropped the bomb first, this is a race without end. No one wins permanently. Instead, more and more countries join. If India is in, then so is Pakistan. Everyone holds a knife to everyone else’s throat. In the review, the United States is suggesting that it will relax, a bit, the pressure from its knife on Russia’s throat while applying more pressure elsewhere. Iraq, for instance, and Syria.

If over the next decade or so, such a weapon could be developed with the purpose of defeating terrorist groups and the United States is attacked again by terrorists, it would be faced with this choice, among several: Does the nation send its soldiers into the equivalent of Shah-I-Kot Valley or does it deploy its limited nuclear weapons? This is the question that worries U.S. allies because if the United States can develop and use such a weapon, why couldn’t – in fact, why shouldn’t – another country?

The Bush administration will spend the next week or two telling allies that this new type of nuclear weapon is merely one idea among many and that it is a long way from actually being a part of this nation’s armory. How much or little these allies – the EU in particular but also Japan – are calmed by this reassurance will give Americans a sense of the level of world trust in the administration. It will provide a sense of their willingness to continue this race without end.