President Yeltsin gave NATO a tough warning over Kosovo yesterday, although alliance leaders were quick to express confidence that Moscow could remain committed to peace efforts.
Hours after he sacked his Prime Minister, Mr Yevgeny Primakov, and created a new domestic political crisis, Mr Yeltsin declared that Russia would pull out of peace moves if NATO did not heed its proposals.
According to a Kremlin spokesman, Mr Yeltsin said Russia would "withdraw from co-operation in negotiations if its proposals and mediation efforts for the Kosovo conflict are ignored".
The Secretary-General of NATO, Mr Javier Solana, played down the significance of developments in Russia for Kosovo diplomacy.
"I am sure that whatever the final result of the change of government in Russia is, the diplomatic process will continue," Mr Solana told Spanish state radio during a brief visit to Albania.
"We are all committed to that diplomatic process. It is going at a good speed, a good pace, and I am sure it will continue."
The French Foreign Minister, Mr Hubert Vedrine, said he was convinced Moscow would remain involved in the search for a diplomatic solution despite a change in cabinet and Mr Yeltsin's warning.
But while Western spokesmen voiced public expectations that Russia would remain constructively engaged, the private reaction in Western capitals was one of some dismay and foreboding.
"This certainly won't make the Kosovo diplomacy any easier. It could complicate things, if Kosovo becomes an object of competing nationalist rhetoric in an aggravated Russian power struggle," one Western Balkans policy-maker said.
In Moscow, in talks overshadowed by the shock of Mr Primakov's dismissal, the US Deputy Secretary of State, Mr Strobe Talbott, met the Foreign Minister, Mr Igor Ivanov, and Mr Yeltsin's Kosovo envoy, Mr Viktor Chernomyrdin.
After their meeting, Mr Talbott and Mr Chernomyrdin mentioned no new proposals for ending the conflict, but both described the talks as helpful.
Mr Talbott left Russia for an overnight visit to Finland, but said he would return to Moscow today for more talks. President Jacques Chirac of France was due to arrive in Moscow late yesterday for Kosovo talks. He sees Mr Yeltsin today.
Mr Chernomyrdin returned on Tuesday from a flying visit to China, which was sucked into the Kosovo crisis by NATO's accidental bombing of its Belgrade embassy last Friday.
Russia's Interfax news agency quoted Mr Chernomyrdin as saying China might be willing to take part in an international peace force for Kosovo if it had Belgrade's support and was organised by the United Nations, not NATO.
But Beijing has refused to take part in any Kosovo peacemaking until NATO stops its bombing, a demand alliance leaders have rejected.
In Tirana, Mr Solana insisted the alliance would keep up the bombing until ethnic cleansing in Kosovo stopped and hundreds of thousands of refugees, driven out by Serb forces, were allowed to return.
Helen Kinghan reports from Brussels: NATO's Gen Walter Jertz said it had been one of the most successful days of the bombing campaign but that at no time in the last 24 hours had NATO found any evidence of a withdrawal of Serbian troops from Kosovo.
The NATO spokesman, Mr Jamie Shea, said: "It is not over yet. It will get harder and harder. We are up against a cynical person who is well dug in but we are going to prevail."
Mr Solana, speaking from a live link at the airport in Albania, said: "I am more and more convinced we have to continue our battle until we see it through." Bringing a message of solidarity to the three countries, Albania, Macedonia and Montenegro, he also met many refugees, NATO troops and the humanitarian organisations working there.
Intense and sustained shelling and fire from Serbian helicopters on Monday in the Pudujeco area resulted in some terribly wounded KLA volunteers arriving in Albania for medical help. There are no details yet of how the displaced people under the protection of the KLA in the area have fared, in the midst of the attacks.