With Kosovo Liberation Army guerrillas taking up positions around Kosovo, U.S. defense officials acknowledged yesterday that NATO has yet to settle on a plan for demilitarizing the rebel group.

NATO authorities opened talks yesterday with KLA leaders in Tirana, the Albanian capital, on a demilitarization agreement. But Pentagon officials said NATO had no firm proposal so far for confiscating the KLA's heavy weapons and bringing an end to the group's existence as a military organization.

The need for an agreement is gaining urgency as KLA fighters take advantage of the withdrawal of Yugoslav forces from Kosovo, claiming control over the southwestern city of Prizren and occupying checkpoints elsewhere around the battered Serbian province.

Crushing the KLA's secessionist revolt was the main objective of a crackdown by Yugoslav Army troops that accompanied NATO's 11-week air war against Belgrade. In the agreement that halted the war and governs the Yugoslav pullout, NATO pledged to demilitarize the guerrillas and assure security for Kosovo's Serbs as well as its ethnic Albanian majority.

Pentagon officials said reaching an accord with the guerrillas has been complicated by the continuing standoff between NATO and Moscow over the role that Russian troops will play in the international peacekeeping force. The KLA is wary of any Russian participation in the NATO-led force because of the traditionally close ties between Russians and Serbs.

Preoccupied with resolving the dispute with Russia and monitoring the withdrawal of Yugoslav forces, U.S. officials sought to play down the lack of an agreed timetable and procedures for demilitarizing the KLA.

"I think it's a question of not being able to do everything at once, which is a fairly standard factor in life," said the Pentagon spokesman, Kenneth Bacon. "The primary goal [of NATO troops] is to get the Serb forces out, and then they will turn to the next tasks."

Brig. Gen. John Craddock, the commander of U.S. forces in Kosovo, said he has instructed his troops to avoid routine attempts to disarm KLA rebels. But he said American forces would intervene if armed KLA guerrillas got too close to the exiting Yugoslav troops or otherwise presented a threat to order and safety.

"Then they are instructed to, in their judgment, if needed, disarm the individual," Craddock told reporters at the Pentagon in a conference call from Skopje, Macedonia.

Other NATO commanders also appeared to have little appetite for a confrontation with the KLA. In Prizren, where KLA fighters toting AK-47 assault rifles were seen directing traffic yesterday and moving into empty Yugoslav Army barracks, German troops responsible for patrolling the sector exchanged waves and salutes with the rebels and made little attempt to constrain them.

Brig. Gen. Fritz von Korff, the senior German officer on the scene, told reporters that he had no orders to disarm the KLA or interfere with it unless the guerrillas hindered his mission. He said, however, that German troops will soon take over a crossing post at Morini on the Kosovo-Albania border, which has been run by KLA guerrillas since Yugoslav authorities vacated it.

The KLA was not a party to the agreement governing the pacification of Kosovo. But rebel leaders have assured U.S. officials of their eagerness to cooperate with NATO and have promised not to carry out reprisals against Yugoslav forces.

At the same time, the KLA has wasted no time spreading back into Kosovo. In addition to setting up checkpoints in Prizren, the rebels have established a headquarters in Pristina, Kosovo's capital. KLA guerrillas also were back in force in the towns of Suva Reka, Kacanic and Stimlje, erecting roadblocks and supervising the return of refugees.

A senior Pentagon official said NATO's plan is to present to the KLA a somewhat revised version of the demilitarization terms that the rebel group accepted after the peace talks in February in Rambouillet, France. Those terms required the KLA to surrender heavy weapons -- machine guns, antitank and antiaircraft weapons and grenade launchers -- within 120 days.

Several draft documents containing a shorter timetable and other changes have been circulating in NATO, but the Pentagon official said alliance authorities have yet to agree on a final position.