Nato officials were due to meet last night in Brussels with officials of the rebel Kosovo Liberation Army to consider requests for bombing missions to support guerilla operations.
The KLA wants air attacks to smash Serb forces which are blocking their efforts to push into Kosovo from neighbouring Albania to link up with forces trapped with thousands of refugees inside the province.
But NATO officials are worried that, in the long term, the KLA intends to establish a dictatorship in Kosovo, and are reluctant to launch military strikes that will help it achieve this.
"NATO will not be the KLA's airforce," said one Western official close to the talks last night. "Can you imagine NATO establishing a protectorate in Kosovo and then the KLA establish a military dictatorship? There's no way the international community is going to have that."
NATO officials are concerned that the KLA appears to be trying to dominate Kosovo's ethnic Albanian political parties, now exiled in surrounding countries.
Militarily, the alliance says such air strikes are possible. The KLA has spent the past week pushing into Kosovo with units being fed in through the northern Albanian border town of Bajram Curri.
It now holds a rectangular piece of mountainous wooded territory, 5 km deep by about 10 km across, anchored on the Albanian border, but the precarious main supply route is constantly targeted by Serbian artillery. Inside the pocket, troops have hit a brick wall - the well-defended village of Junik, south west of the town of Decani. Beyond Junik is the north-south highway used to move Serbian troops, and the scene of NATO's erroneous attack on a refugee convoy earlier this month. Beyond that are more guerrilla units close to the village of Glodjane.
The KLA says that forming a link would allow it to get refugees out and new fighters in.
A primitive communications link has now been established between the KLA and NATO, via a satellite fax/phone operated inside the province. Faxes are sent to three KLA officials in Brussels, who in turn relay these to NATO.
In the past four weeks NATO has launched several air strikes after being alerted through the KLA phone link. But the Junik operation would mark a new stage in their co-operation, with strikes needing some form of ground observation and lasting several days.
A more daring alternative might be to use the American airborne troops now arriving in the region to establish a "safe haven" in this area, although it is unlikely that such an operation would meet NATO's desire for "zero casualties" among its own troops.
More likely, if NATO agrees, would be that bombers would open the corridor, and the Apache attack helicopters now in Albania would help keep it open, fending off Serbian counter-attacks.
The Western alliance may fear becoming air support for the KLA, but it also fears sending its own ground troops into the province, and may welcome the chance to let another army do the work.
But first are likely to come the political questions - made harder because the KLA has yet to speak with one voice. Since it began fighting in late 1997, the KLA has been riven by disputes and disagreements. NATO officers are worried about the KLA's attitude to its main political rival, Mr Ibrahim Rugova, elected president in unrecognised elections among ethnic Albanians last year.
Mr Rugova, since captured and apparently kept prisoner by the Serbs, was denounced as "worse than a traitor" by KLA spokesman Mr Jakob Krasniqi last week.
NATO will want assurances that, if victory comes, the KLA will confine its battles with Mr Rugova to the ballot box.