LONDON, Oct 1 (Reuters) - After months of dithering, Western countries are steeling themselves for possible military action against Serbia, but experts question whether air strikes without a ground deployment can solve the Kosovo problem.

NATO officials stress that tough talk from Western ministers and high-profile military planning by the alliance are designed to force Yugoslav President Slobodon Milosevic to yield without having to fight.

"The strategy is to avoid the use of force, if we can, by exerting the maximum political and diplomatic pressure," said a diplomat at NATO headquarters. "Nothing leads us to believe that President Milosevic will not back down when he sees the West is deadly serious about action."

The next week could be decisive in determining whether or not Western air forces launch massive strikes on Serbian forces.

U.N. Secretary-General Kofi Annan reports to the Security Council, perhaps as early as Monday, on whether Milosevic has complied with last week's resolution demanding a ceasefire.

Further details are likely on who carried out massacres of ethnic Albanian civilians in Kosovo. The six-power Contact Group in charge of Balkan peace efforts will have met in London and European Union foreign ministers meet next Monday in Luxembourg.

"We are putting ourselves under a lot of pressure to act. We would look ridiculous if we didn't do something after all this preparation and talk, as happened in June," a French official said.

But amid a rising torrent of rhetoric, led by Robin Cook, Britain's sharp-tongued foreign secretary, independent analysts and experienced military men query whether the West has a coherent strategy.

"There seems to be a patent mismatch between the means and the objectives," said a senior serving military officer who commanded NATO peacekeepers in Bosnia.

"It's not at all clear how you could use air power to force a sovereign state to grant one of its provinces autonomy, especially when people there are fighting for independence, not autonomy," said the general, speaking on condition of anonymity.

Colonel Terence Taylor, assistant director of the International Institute of Strategic Studies, said air strikes would have to be accompanied by a land campaign to be effective.

"The history of the use of air power since World War Two shows that on its own, it doesn't work," Taylor said.

NATO sources acknowledge that, while planning for a phased air campaign, beginning with strikes on Serbia's air defences, is virtually complete, preparations for a ground operation are at a much more rudimentary stage.

"We would have to have very rapidly available ground troops able to enforce any ceasefire or initial settlement and secure the ground for humanitarian relief operations, refugee return, international observers and deter the Kosovo Liberation Army (KLA) from exploiting a Serb withdrawal," a NATO diplomat said.

"We haven't reached that point yet. We have to finalise the planning and we haven't even started the force generation for ground operations," he said.

Force generation is NATO jargon for member states pledging troops for an allied operation. Many analysts doubt whether the United States, given congressional hostility to open-ended military engagements, could offer ground troops for Kosovo.

Professor Lawrence Freedman, head of war studies at London University's Kings College, said the Kosovo situation reminded him of the Western allies' attempt to create a safe haven for the Kurds in northern Iraq after the 1991 Gulf War.

"To police the safe haven by air power without troops on the ground may be the best model, but it didn't stop the war between the Kurds and the Iraqis, or civil war among the Kurds. Nor would it in this case," Freedman said.

"If not clearly backed by force on the ground as well in the air, it may not provide enough confidence for refugees to return home, and it could end up just providing a safe haven for the KLA," he said.

NATO governments are aware of the danger of appearing to act as the "KLA air force".

Any military action against Serbia would be accompanied by a warning to the KLA that NATO could not restrain the Serbs if guerrillas began attacking Serb police stations again.

But given the separatists' fierce determination, and their loose organisation, some analysts doubt whether such a warning would be heeded.

To avert air strikes, NATO would expect Milosevic to reach agreement with the United Nations to withdraw army and special police forces from Kosovo on condition the KLA did not exploit the situation. Leaders of the Kosovo ethnic Albanian majority would have to give an undertaking to refrain from violence.

Milosevic would also have to agree to a U.N. plan for the return and resettlement of up to 300,000 refugees driven from their homes by the fighting.

And he would have to commit himself to a timetable for negotiating autonomy, preferably under international mediation, NATO diplomats said.

While most European NATO allies would prefer a further Security Council resolution before using force, even sticklers such as France appear to be willing to contemplate taking action without another vote if Russia will not support the West.

The French official said last week's resolution had laid the groundwork by defining the situation in Kosovo as a threat to peace and security under Chapter VII of the U.N. Charter and threatening further measures if Milosevic did not comply.

"The idea of avoiding a Russian veto is gaining ground. We cannot sit on our hands," he said.