WASHINGTON, Feb. 2 (Xinhua) -- U.S. President Barack Obama on Wednesday signed the new START treaty with Russia, which is designed to replace the previous accord that had expired in December, 2009.

Under the new treaty, each country must limit their nuclear warheads under 1,550 respectively, a roughly 30 percent less than the previous treaty.

The new nuclear arms treaty was approved by the U.S. senate at the end of last year, and by the Russian lower parliament in January. The Obama administration has considered the treaty as an important milestone to "reset" U.S.-Russian relations.