Obama seeks momentum from Russia in arms pact signing

US president Barack Obama leaves on Wednesday for Prague where he will sign a landmark nuclear treaty with Russia, marking a much-needed diplomatic achievement and a step toward better ties with Moscow.                                           

Obama hopes the agreement committing the two former Cold War foes to new cuts in their nuclear arsenals will help further his goal of a world without atomic weapons.                                           

The signing of the pact with Russian president Dmitry Medvedev on Thursday comes two days after Obama unveiled a new US policy restricting the use of atomic weapons. Next week, a 47-country nuclear summit will be held in Washington.          

The event at the medieval Prague castle is taking place near the anniversary of a speech he gave in the Czech capital vowing to seek "the peace and security of a world without nuclear weapons."                 

Just before the signing, Obama will hold private talks with Medvedev. In the evening, he will dine with 11 heads of state from Eastern and Central Europe.                                           

Obama will press Medvedev in their meeting to support tougher United Nations sanctions against Iran, a message he will also push in Washington during his meeting with Chinese president Hu Jintao on the sidelines of the April 12-13 nuclear security summit.                                           

Andrew Kuchins, a Russia expert at the Center for Strategic and International Studies think tank, said Iran would likely be the "principal issue" in the Obama-Medvedev meeting.              

"It will be important to work out something closer to an agreement with the Russians about the language in the areas on sanctions before negotiating with the Chinese," he said.                       

The two largest nuclear powers reached the arms reduction agreement last month after nearly a year of negotiation.        

The treaty, a successor to the 1991 Strategic Arms Reduction Treaty, would limit operationally deployed nuclear warheads to 1,550, down nearly two-thirds from START I.                           

Obama has put a priority on trying to "reset" relations with Moscow that hit a post-Cold War low during Russia''s 2008 war with Georgia. The treaty could improve the tone of the relationship.