[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2010/images/08/11/art.hillaryclinton.gi.file.jpg caption =" Secretary of State Hillary Clinton asked lawmakers to ratify a nuclear arms treaty with Russia on Wednesday."]
Washington (CNN) - Secretary of State Hillary Clinton urged Senate ratification of the new nuclear arms treaty with Russia on Wednesday, stressing that it's a critical component of U.S. efforts to keep tabs on Moscow's arsenal.
"It will advance our national security and provide predictability and stability" between the world's top two nuclear powers, she told reporters at the State Department.
The Strategic Arms Reduction Treaty signed in April by President Barack Obama and Russian President Dmitry Medvedev cuts the total number of nuclear weapons held by the United States and Russia by about a third. Specifically, it fixes a ceiling for each country of 1,550 nuclear warheads and 700 deployed nuclear delivery vehicles.
Some top Senate Republicans, however, have expressed skepticism about the accord, arguing that it complicates U.S. efforts at developing a missile defense system.
"Opposing ratification means opposing the inspections (that) provide us a vital window" into Russia's nuclear arsenal, Clinton warned. "As time passes, uncertainty will increase," leading to greater unpredictability.
The last START treaty expired in December.
The Senate Foreign Relations Committee is set to begin formal consideration of the new accord in mid-September, Clinton said.
The treaty needs 67 votes in the Senate to be ratified.