WASHINGTON - US President Barack Obama and his Russian counterpart Dmitry Medvedev on Thursday discussed the new START treaty on the phone, said the White House in a statement.

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The White House said the two spoke by phone on Thursday morning to discuss the new START treaty, as well as continued close cooperation on a range of critical issues.

"President Medvedev congratulated President Obama on the (US) Senate's approval of the new START treaty, and the two leaders agreed that this was a historic event for both countries and for US-Russia relations," said the White House.

The US Senate voted on Wednesday to ratify the new nuclear arms treaty with Russia, delivering President Obama his top foreign policy goal as the lame-duck Congress session draws to an end.

Obama and Medvedev signed the treaty in April, which caps the deployed nuclear warheads in each state to no more than 1,550 over seven years, a cut of 30 percent over the current ceiling of 2,200 set in 2002, limits the number of deployed ballistic missiles and nuclear bombers to no more than 700 each, and sets up a mechanism for verification and inspection.

The treaty needs to be ratified by the Russian parliament before it comes into effect. The Russian parliament may ratify the new strategic arms reduction treaty (START) as early as Friday, the lower chamber's chairman, Boris Gryzlov, said on Thursday.