Germany had asked the US to consider moving Nato to a policy of "No First Use". This would commit the organisation not to use nuclear weapons unless they had been used against Nato first.
However, America says it still considers the "uncertainty" generated by Nato's current policy to be vital in deterring not only nuclear attacks but chemical and and biological assault as well.
"The US opposes any change in this policy because we believe the current doctrine serves to preserve the peace and enhance deterrence," the US Defense Secretary, William Cohen, said.
The policy creates "uncertainty in the mind of any aggressor about the nature of the allies' response to any military aggression" and there is "no reason to consider changing it," Mr Cohen.
Washington also believes that by simply threatening nuclear attack, it helps to reassure allies such as Japan that it will defend them against attacks.
Rudolf Scharping, the German defence minister, was on a trip to Washington yesterday, and the US has used his visit as the occasion to pre-empt any discussion of nuclear strategy.
Nato is currently revising its Strategic Concept, the alliance's military foundation, and both Germany and Canada have said they would like to start a debate about nuclear matters and shift the alliance towards "No First Use".
In Germany, pressure is coming from Joschka Fischer, the Foreign Minister and a member of the Green Party.
"It is an integral part of our strategic concept and we think it should remain exactly as it is," Mr Cohen said. "We think it is a sound doctrine. It was adopted certainly during the Cold War, but modified and reafffirmed following the end of the Cold War," he said.
America is prepared to reduce its nuclear weapons, however, if Russia next week ratifies the Start II nuclear arms treaty. The pact, agreed in 1997, would cut the number of nuclear warheads on both sides from about 6,000 to 3,500, and America is offering early deactivation of these warheads.