MOSCOW, November 30 (RIA Novosti) - The Russian and U.S. presidents discussed a new bilateral arms reduction treaty in a phone conversation on Monday, the Kremlin said.

Moscow and Washington are negotiating a replacement for the Strategic Arms Reduction Treaty (START I), the basis for Russian-U.S. strategic nuclear disarmament, which expires on December 5.

Dmitry Medvedev and Barack Obama "touched on issues of future cooperation between Russia and the United States in stabilizing the situation in Afghanistan, and also discussed progress in preparing a new treaty on strategic arms reduction," the Kremlin said.

An outline of the new pact was agreed during a summit held by Obama and Medvedev in Moscow in July, and includes cutting their countries' nuclear arsenals to 1,500-1,675 operational warheads and delivery vehicles to 500-1,000.

Obama also conveyed his condolences to the families of those killed in last Friday's terrorist attack on a train travelling from Moscow to St. Petersburg.

A total of 26 people have been confirmed dead following the derailment of several carriages of the Nevsky Express, and two remain unaccounted for.