President Yeltsin, seeking the moral high ground over the United States, said last night that he had signed a draft law approving the Comprehensive Test Ban Treaty, and sent it to parliament for ratification.
The US Senate dealt President Clinton an embarrassing blow on October 13th by rejecting the CTBT, drawing widespread international condemnation.
Earlier Russia sent a clear military signal to the West on the eve of today's European security summit in Istanbul. The Russian navy test-fired two nuclear-capable missiles from a huge Arctic submarine yesterday just as President Yeltsin was heading for the Organisation for Security and Co-operation in Europe (OSCE) meeting.
Russia's navy said the missiles were launched within two hours of each other from the Barents Sea in the far north-west and the warhead sections hit a Russian testing ground on the easternmost peninsula of Kamchatka.
"The successful test of the two missiles from the nuclear submarine showed the high level of preparedness of the combat command system and personnel training," navy spokesman, Mr Igor Dygalo, said in the statement.
Mr Yeltsin said he had signed the bill on the CTBT and sent it to the Duma before flying to Istanbul. "Today, I have signed the draft law on ratification of the Comprehensive Test Ban Treaty. This means that Russia is making its concrete and real contribution to strengthen the nuclear non-proliferation regime and strategic stability in the world.
"I call on all states to follow this example," he told journalists after meeting President Suleyman Demirel of Turkey.
Russia signed the treaty in September 1996 but, of the five official nuclear powers, only France and Britain have completed ratification so far.
President Yeltsin is expected to face strong criticism in Istanbul from the West over Russia's military campaign in Chechnya and will take a tough line himself. Yesterday, Russian forces intensified their offensive in the Caucasian region.
Mr Yeltsin is due to meet the US President, Mr Clinton in Turkey. Relations between the two are frosty not just because of Chechnya. They have profound differences over arms control, including US plans for a national anti-missile shield which would violate the 1972 Anti-Ballistic Missile Treaty (ABM).
Mr Yeltsin has said he will use his political weight to change Western attitudes to Russia's military campaign in Chechnya, which looks likely to dominate the summit.
Western leaders, including Mr Clinton, have voiced increasingly loud concern over what they say is Moscow's excessive use of force in the region.
Mr Javier Solana, the EU's foreign policy supremo, urged Russia to end its "disproportionate" use of force in Chechnya. "We must continue to put maximum political pressure on the Russian authorities," Mr Solana, the EU's High Representative for Common Foreign and Security Policy, told the European Parliament in Strasbourg.
The trip is a rare visit abroad by Mr Yeltsin, who has suffered a bout of physical ailments in recent months.
Russia accused NATO of bypassing the United Nations during its 11-week aerial bombardment of Yugoslavia to end repression against Serbia's mainly ethnic Albanian province of Kosovo.
However, Mr Yeltsin said yesterday that Russia would back a European security charter provided no last-minute changes were made to the document.
The Foreign Minister, Mr Igor Ivanov, who is with Mr Yeltsin in Istanbul, said that Russia was ready to take a "constructive approach" to the Chechnya conflict at the Istanbul summit.
But he warned that "if any country tries to politicise the problem [of Chechnya], to use it against us, it would become very difficult to have a constructive atmosphere at the summit."
But while the Russian leaders sought to clear the air in meetings with their western counterparts, Moscow's military was back on the offensive intensifying overnight bombardment of the Chechen capital. Chechen officials said 54 civilians had died in the last 48 hours of bombing.