Under the treaty, the two sides must reduce their deployed strategic nuclear warheads to no more than 1,550 in seven years and reduce deployed long-range missiles and bombers to no more than 700.
Some of the initial steps required by the accord:
* Once the treaty enters into force, the sides will immediately begin exchanging information about the status of their nuclear forces, a senior US official said on condition of anonymity. For example, they will notify each other whenever nuclear arms are deployed or removed from deployed status. The information is channeled through Nuclear Risk Reduction Centers established by both sides in 1988. The US centre is at the State Department and the Russian center is at the defense ministry.
* Within 25 days, the two sides must exchange the names and details of no more than 300 people who may serve as inspectors. The sides also will exchange the names of air crew members who will fly the inspectors. Within 30 days of the list exchange, the sides must issue visas for the inspectors and air crews.
* Within 45 days, the two sides must carry out an initial exchange of detailed information on each other's nuclear arsenals. We'll exchange a complete database, the US official said. We'll give the Russians a complete set of data about our strategic nuclear forces and they'll give us a complete set of data about their strategic nuclear forces.
The data will include detailed information like a missile's classification, number of stages, length without front section, diameter of airframe, total length with launch canister and type of propellant.
* Sixty days after the treaty enters into force, the two sides may begin conducting on-site inspections.
Probably in mid-April or so the first inspection will take place, assuming the instruments of ratification are exchanged in the first half of February, the US official said.