BONN, AUG. 1 -- If West Germany owns a nuclear missile, but the United States controls the warhead, then who's in charge?

This question about 72 antiquated Pershing IA missiles is at the core of one of the last remaining disputes blocking a U.S.-Soviet treaty on medium- and shorter-range missiles.

The Pershing IAs originally were placed under joint U.S.-West German control 20 years ago to give Bonn a role in NATO's strategy of nuclear deterrence. West Germany cannot control the warheads because of a pledge in the Paris and London agreements of 1954 never to own nuclear weapons.

Now, negotiators in Geneva tentatively have agreed to destroy all U.S. and Soviet nuclear missiles and warheads with ranges of between 300 and 3,500 miles.

The Pershing IAs, with a range of about 460 miles, fall in the category of weapons to be scrapped. But the negotiators still are deadlocked over verification issues, and whether to count the Pershing IAs as American or West German weapons.

If they're German, as the Americans say, then they must be excluded from the treaty and therefore can remain deployed in West Germany. The Geneva negotiations are bilateral, between the United States and the Soviet Union.

The Americans point out that the Geneva talks always have counted nuclear weapons in terms of launchers or missiles, mainly because warheads are too small to be verified by spy satellites. The Pershing IA launchers and missiles are West German-owned, so the entire system is German, the Americans say.

"We've warned the Soviets: don't make us choose between the treaty and an ally. We would have to choose the West Germans," a U.S. official said.

Western officials concede, however, that the Soviets are scoring public relations points by contending that the Pershing IAs' warheads must be destroyed under the accord. The West Germans can keep their missiles, but the U.S.-controlled warheads have to go, the Soviets say.

Moscow also points out that it would be foolish to dismantle all of its 130 missiles in the Pershing IAs' range while allowing NATO to keep the 72 Pershing IAs.

The disagreement over whether the Pershing IAs are American or German also undermines possibilities of a compromise proposed this week by senior Soviet officials. The Soviets suggested that the Pershing IAs could remain, but then the Soviets would keep a roughly equivalent force of their own missiles of similar range in East Germany and Czechoslovakia.

This is unacceptable to the Americans, because the United States cannot agree at Geneva to match West German missiles against Soviet ones.

The question of who controls the Pershing IA also is causing subtle strains within NATO. The United States and West Germany each believes that the other should take the lead in crafting a compromise over the issue, according to U.S. and West German sources.

Chancellor Helmut Kohl fears a major fight if his quarrelsome, center-right coalition has to decide the issue on its own, according to government and political sources. If a deal is to be struck, Kohl's government would like the United States to take the initiative and essentially present Bonn with a fait accompli, according to West German sources.

The logic of the Americans' position at Geneva, however, compels Washington to argue that the West Germans must take primary responsibility for any decisions regarding the Pershing IA.

In another sign of NATO disarray on the issue, Britain and France reject one of the main U.S. arguments for why the Pershing IAs should be left out of the negotiations.

London and Paris believe that the Pershing IAs are not strictly "third-country systems" -- as Washington maintains -- because the United States has a say in firing them, according to British and French officials.

As a result, the British and French are concerned that the Americans' argument at Geneva over the Pershing IAs could backfire in the future to the allies' detriment, the officials said.

If the Americans ultimately compromise on the Pershing IAs, then this could weaken the British and French position that their missiles, which can be launched without U.S. clearance, must be excluded from future U.S.-Soviet arms control agreements.

The British and French instead endorse the second U.S. argument for excluding the Pershing IAs from the Geneva talks. Under this argument, the Pershing IAs represent an "established pattern of cooperation" between the United States and West Germany, and such cooperation between Washington and one of its allies may not be affected by a bilateral, U.S.-Soviet treaty.

The most likely compromise on the Pershing IAs would provide for the West Germans to keep them for the moment, but agree not to replace them with more modern missiles, according to government, political and diplomatic sources.

The Pershing IAs are scheduled to be scrapped within five years because of their age, so they would be "retired" while the American and Soviet missiles were being dismantled in phases under the treaty.

Two senior Soviet officials said this week, however, that such a compromise was unacceptable. Washington Post correspondents Karen DeYoung in London and Edward Cody in Paris contributed to this report.