Under the treaty, Russia and the United States agree to limit the number of nuclear warheads to 1,550 each, down from the ceiling of 2,200. The pact also establishes a system for monitoring and verification. The treaty was signed by Obama and Russian President Dmitry Medvedev on April 8.
Ratification required 67 votes. Passage seemed assured on Tuesday when 11 Republicans joined 56 Democrats to vote for cloture on the measure.
Read more at New START: Senate passes New START treaty – latimes.com.