Ian Kelly, a spokesman for the United States Department of State, said the signing of a new arms treaty between Russia and the U.S. is impossible before the deadline of December 5.

"Well, I think - I mean, clearly it''s going to be impossible to have a ratified treaty by December 5th," Kelly said at a daily press briefing.

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

An outline of the new pact was agreed during the Russian and U.S. presidents'' bilateral summit 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.