MOSCOW, November 17 (RIA Novosti) - The U.S. ambassador said Russia and the United States have good chances of signing a new nuclear arms reduction treaty this year.

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.

John Beyrle said in a Gazeta.ru interview differences remain, but "the political will expressed by both presidents... will prompt the negotiators to find compromises in the next few weeks."

The presidents met in Singapore on Sunday and said an additional impetus must be given to the negotiations.

Moscow and Washington were reported to differ on the control of mobile missile systems and cuts in delivery vehicles. Russia has also sought to link the new treaty to limits on the deployment of ballistic missile defense systems as the U.S. has unilaterally withdrawn from the ABM treaty.

An outline of the new pact was agreed during Dmitry Medvedev and Barack Obama's 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.

Speaking on the Cold War-era Jackson-Vanik trade restriction, Beyrle said he hopes Congress will lift it next year.

The ambassador said the amendment "has had no major effect on our relations," but "could play a psychological role."