Allies Scramble to Close NATO Rift. Thatcher works to rally European leaders around need for nuclear modernization. DIPLOMACY AMONG FRIENDS

WITH only one month to go before a key NATO summit meeting, Western allies are split over the issue of deploying short-range nuclear forces in Europe - and compromise appears remote. The rift threatens the solidarity of the alliance as it engages in wide-ranging arms-control talks with the Warsaw Pact and confronts Soviet leader Mikhail Gorbachev's persuasive public diplomacy in Western Europe.

Mr. Gorbachev is scheduled to visit Bonn in June, two weeks after the May 29-30 summit meeting in Brussels. Defense analysts in London want NATO to resolve the disagreement before the popular Soviet leader again voices his message of a nuclear-free Europe and possibly announces further arms-control initiatives.

These analysts are worried that he could turn West European public opinion strongly against NATO's continued deployment of short-range nuclear weapons and weaken an already shaky coalition in West Germany.

``What will Mr. Gorbachev say in West Germany?'' asks Andrew Duncan, a defense expert at the London-based International Institute of Strategic Studies. ``He could well make a big gesture on unilateral reductions in short-range nuclear weapons, and what effect would this have on West German voters?''

Some British defense officials say that Gorbachev has already driven a wedge between West Germany and other NATO allies. Bonn has suddenly broken with NATO policy and proposed accepting the Warsaw Pact's offer to hold talks on reducing the numbers of NATO's short-range nuclear missiles, including for the first time nuclear artillery. This raises the possibility of the so-called ``third-zero'' option, or the elimination of short-range nuclear weapons from Western Europe.

The West German government also wants to postpone any decision on the modernization of short-range nuclear (Lance) missiles until at least 1992 with deployment after 1996, depending on the outcome of arms-control negotiations. West German Chancellor Helmut Kohl has described these proposals as Bonn's negotiating position within NATO, as it seeks a common policy on mutual defense in the 1990s.

NATO officials say they thought they had reached an understanding with Bonn on the need for modernization in a document signed last week. But the same day the West German press leaked the text of a secret agreement among the government's coalition partners which called for early talks with Moscow and a postponement on new weapons.

West German Foreign Minister Hans Dietrich Genscher said that his government is united in these proposals. Mr. Genscher is the leading advocate of early talks, while Chancellor Kohl had generally upheld the NATO view.

With Kohl's shift in position, apparently under pressure from his political partners, British officials are worried that his right-of-center coalition is unstable, and that elections next year could bring to office a government that is less resolute on defense.

London and Washington oppose the West German proposals, particularly the offer to negotiate reductions in short-range missiles. Their elimination could increase the threat to NATO forces from the Warsaw Pact, British defense officials say.

``Without short-range nuclear weapons and without reductions in the Warsaw Pact's conventional weapons, NATO would be vulnerable to conventional attack,'' Colonel Duncan says.

NATO deploys 88 launchers for Lance missiles which, with a range of 150 miles, could interdict tank assaults by the Warsaw Pact. NATO officials have called Lance the ``most credible deterrent'' to Soviet superiority in conventional forces.

The alliance policy, previously endorsed by Chancellor Kohl, is that before short-range weapons are placed on the negotiating table, there must be progress in reducing conventional, chemical, and strategic nuclear weapons.

With Washington and London united in their opposition to talks on short-range weapons, there appears to be little room for compromise on the question of negotiating reductions, though there may be some flexibility on the question of modernizing Lance.

Lance technology dates from the 1950s and '60s, and the Pentagon says the missiles should be replaced by the mid-1990s. The US Congress is waiting for a NATO commitment before it authorizes development funds for the modernization program, estimated at $1 billion.

In a meeting with Kohl this weekend, British Prime Minister Margaret Thatcher is expected to stress that NATO cannot postpone any longer a decision to modernize. She will emphasize the fact that, according to NATO sources, the Soviets have already modernized their own 1,600 short-range nuclear weapons and that NATO should do the same.

Mrs. Thatcher is also working to persuade the Italian and Dutch prime ministers to support her views. Meanwhile, Belgium has come out in support of West Germany's proposal for early talks and postponing a decision on modernization.

Visiting London to commemorate the 40th anniversary of NATO, Manfred W"orner, NATO's secretary general, said the alliance wanted only the minimum nuclear and conventional weapons for its defense and that ``those have to be kept up to date.''

As a former West German defense minister, he indirectly urged the Bonn government to show stronger leadership on defense issues and not abandon its previous policies.

Mr. W"orner denied that the Soviets had driven a wedge into the alliance on these issues and insisted there was still the possibility of a reasonable compromise before the May summit. He also said that the modernization of short-range weapons were not the most important item on the agenda for the Brussels summit meeting.

``The centerpiece of the summit will be a political message concerning the future of this alliance, the future of East-West relations, how to shape the next decade, what are our goals, how will we achieve them,'' W"orner said.

Unless some compromise is reached before the summit, however, analysts in London say that the strategic purpose of the meeting could be diminished and its political message muted.

``This has got to be solved politically rather than militarily ... It's a battle for public opinion,'' Duncan said.