Russian arms control treaty is more important for the diplomatic bargain it seals with a restive Russia than for the limits it places on weapons that neither side was likely to use, treaty or no treaty. Despite skepticism from Republican opponents who worry that the United States would be purposely fraying its nuclear advantage, the Obama administration considers the pact a disarmament bargain because it probably will help cinch Russian cooperation with an American plan to protect Europe with an anti-missile shield arrayed against Iran. Presidents Barack Obama and Dmitry Medvedev have called the agreement historic and the capstone for a “very productive year” of cooperation on issues including Iran sanctions and the war in Afghanistan. Medvedev already had welcomed the US Senate's decision to ratify the landmark nuclear arms control treaty, while Russian legislators said they need to study a resolution accompanying the document before following suit. The Senate voted 71-26 to ratify the treaty, and Russian legislative approval is expected quickly. The Senate approval was a clear victory for the White House after weeks in which it seemed doubtful that President Obama could muster enough Republican votes. Obama had called approval of the treaty his highest foreign policy priority this year. “This is the most significant arms control agreement in nearly two decades,” Obama said shortly after the Senate approved the treaty Wednesday. He asserted that the treaty “will make us safer” and point out that it would allow US inspectors to return to Russian nuclear bases. Obama and Medvedev signed the treaty in April with bonhomie intended to show that the pact was about making things right with Moscow as well as reducing warheads. Russian leaders let it be known they considered the treaty a test of Obama's sincerity and clout. The New START treaty replaces the expired Strategic Arms Reduction Treaty of 1991. It sets a limit of 1,550 strategic nuclear warheads for each side, down from 2,200 under a 2002 deal. The pact also re-establishes anti-cheating procedures that were not written into the 2002 accord, thus providing the most comprehensive and substantial arms control agreement since the 1991 treaty. But that ambitious nuclear downscaling was jeopardized when Obama won NATO support in November to build a missile shield over Europe. The commitment to erect the shield, ostensibly aimed at Iran, remained one of the major irritants with Russia until Obama scrapped plans to stage parts of it at Russia's doorstep. His reworked missile shield plan got a polite but noncommittal reception from Moscow, and Obama's advisers breathed a cautious sigh of relief. A public fight with Russia over missile defense might have sunk the new treaty with just weeks to go before the close of the current congressional session. With Senate approval, the administration can fully exhale. Carrying the treaty over into 2011 would have made it harder to pass, and rubbed salt in already-sensitive Russian irritation at the slow pace of US approval and at Republican suggestions that parts of the treaty might have to be reworked. Obama and Senate Democrats backing the treaty claimed that getting inspectors back on the ground in Russia is so urgent that the United States could not afford to put off a vote on the treaty to next year. That blurred the real reason Obama wanted to move now: He faces a larger Republican contingent in the Senate, although still a minority, when the new Congress takes over in January, any Republican effort to alter the pact would anger Russia and make Obama look less trustworthy in Russian eyes.