Barack Obama said the agreement, which will pave the way for new cuts in American and Russian nuclear arsenals, was the most important such deal in almost 20 years.

After months of wrangling in the Senate, the New Start treaty was passed by a vote of 71 to 26.

Under the deal, Russia and the US will cut deployed nuclear warheads by 30 percent.

Despite lengthy protests from a number of congressional Republicans, 13 Republican Senators voted with the Democrats during Wednesday's vote.

Top Republicans, including Minority Leader Mitch McConnell, John McCain and Jon Kyl, had opposed ratification of the treaty.