Obama signed the documents in the Oval Office surrounded by key senators and top national security and military officials, including Secretary of State Hillary Clinton and Secretary of Defense Robert Gates.

The new Strategic Arms Reduction Treaty slashes existing warhead ceilings by 30 percent over the next 10 years and limits each side to 700 deployed long-range missiles and heavy bombers.

Russian President Dmitry Medvedev signed the new START agreement's ratification on Friday after the Russian parliament passed the pact, which was endorsed by the US Senate last month.

The deal enters into force the moment the two sides swap their respective "instruments of ratification."

Russian diplomatic sources and US officials said the ceremony will be held during the February 4-6 Munich Security Conference -- an annual gathering of some of the world's most senior defense officials and experts.

Clinton and Russian Foreign Minister Sergei Lavrov are expected to preside.

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