Russia's parliament has given its backing to the Start nuclear arms disarmament treaty. The Federation Council or upper house unanimously approved the deal signed by US President Barack Obama and Russia's Dmitry Medvedev in April 2010. Vote by the upper house comes a day after the treaty was ratified by the Duma, or lower house, and represents the final step in its passage through parliament. Under the agreement, the number of nuclear warheads deployed by each country will be cut to 1,550. The US Senate approved the treaty by 71 votes to 26 last year, after months of wrangling. The new Strategic Arms Reduction Treaty (Start) will replace its predecessor, signed in 1991, which lapsed at the end of 2009.