In what President Bill Clinton described as "a milestone in enhancing strategic stability", the US and Russia yesterday agreed to set up the first joint early-warning centre in Moscow, aimed at reducing the chances of a nuclear war being launched by accident.
It is scheduled to begin operation by next autumn and would run for 10 years, senior US officials said.
The initiative was prompted by US alarm at the dilapidated state of Russia's system of satellites and radar facilities monitoring ballistic missile launches. A pilot programme involving US and Russian military personnel was conducted in Colorado at the end of last year.
"The purpose of this whole effort is to provide a near real-time exchange of the detected information about the launch of ballistic missiles and space-launch vehicles that are detected by the warning systems of the two sides," said a senior US official yesterday at the end of Mr Clinton's two-day summit with President Vladimir Putin in Moscow.
"It will be the first time that American and Russian military personnel will be permanently involved in a joint military operation over an extended period." he added. The US and Russian leaders also announced agreement on a deal costing almost $6 billion which would dispose of 68 tonnes 34 tonnes each - of weapons-grade plutonium over the next 20 years.
Mr Clinton said that the plutonium being put into storage or civilian nuclear energy projects was enough to build thousands of warheads.
"It will never now fall into the wrong hands," he declared.
The disposal of the US plutonium would cost $4 billion, the Russian $1.75 billion. US officials said other unnamed countries would be expected to contribute to the cost.
The agreement stipulates the "safe, transparent and irreversible" disposal of the plutonium. Neither side would be able to use the plutonium for military purposes.
Reflecting US unease at the Russian supply of nuclear materials and technology to Iran, where Moscow is building a power plant at Bushehr, Mr Clinton said he had insisted on "strict export controls".
Mr Putin has just signed a decree making it easier for Moscow to strike commercial deals for exports of civilian nuclear technology, a move that has alarmed western nuclear proliferation experts.
US officials said the Moscow centre, which entailed 16 US and 17 Russian military officers working shifts 24 hours a day and seven days a week, would use space-based satellites, infrared systems, and early-warning radar.
But the Americans also hope that the establishment of the centre will reduce stiff Russian opposition to US plans for a national missile defence system, the sore point of the weekend summit, by helping to persuade them that it was no threat to strategic stability and the Russian nuclear deterrent.
"The purpose is to avoid the possibility of false warning of attack . . . But there are other purposes that are also served by the creation of this centre," admitted the US official. "One of those purposes is to increase the mutual confidence between the sides about the effectiveness of their early warning systems. And it also is a way to focus attention on the continuing worldwide proliferation of ballistic missiles."
In the event of a missile launch from the US or Russia - and within a minute - information on launch site, type of missile and timing of impact would be shared.
This would eliminate "uncertainties" about the intention of any launch.
Information about launches by other countries will also be provided, but only if the missile or spacecraft is crossing the territory of the US or Russia, the official said.