Senior Russian officials warned yesterday that Moscow increasingly saw no point in continuing an exercise that was getting nowhere.
The decision could be taken within a week or so, they say, if Mr Chernomyrdin's next visit to President Slobodan Milosevic in Belgrade, tentatively planned for Thursday, yields no fruit.
In a sense, their remarks merely echo threats already uttered by President Boris Yeltsin. But they are clearly an effort to unnerve some Nato countries at a point when signs are growing that Belgrade's resolve may be weakening.
"Perhaps the Russians are getting cold feet," one defence analyst said last night. "They could be getting their own intelligence reports that Milosevic is starting to lose support. Maybe, too, they are starting to believe that after upping its military force in the region to 50,000, Nato really might invade."
Russian domestic politics, and the country's instinctive support for Mr Milosevic, are almost certainly reasons too.
Although Mr Chernomyrdin is adamant he will not act as a "postman" for Nato, that in effect is what he largely is. That perception would damage his cause if he still entertains hopes of a presidential bid to succeed Mr Yeltsin next year. Mr Milosevic is reported to have little faith in the Russian envoy, believing him to be too close to Nato's position.
A Russian pull-out could cause ructions within the alliance, just as it seems to be putting a fortnight of disunity behind it.
Germany, which especially insists on co-operation with Moscow, is certain to be unnerved, while Nato's hopes of getting a United Nations resolution - widely seen as essential for a final settlement - would again be totally at the mercy of a Security Council resolution.
Russia's two biggest complaints are about the West's insistence that the core of the peace-keeping force must be provided by Nato, and its refusal to consider a bombing halt until Yugoslav forces start to pull out of Kosovo. "At the very latest, the bombing must stop when there's a security council resolution," one Russian diplomat said last night.Reuse content