From the Summary: "The United States and Russia signed the New START [Strategic Arms Reductions Treaty] Treaty on April 8, 2010. After more than 20 hearings, the U.S. Senate gave its advice and consent to ratification on December 22, 2010, by a vote of 71-26. Both houses of the Russian parliament--the Duma and Federation Council-- approved the treaty in late January 2011 and it entered into force on February 5, 2011. Both parties met the treaty's requirement to complete the reductions by February 5, 2018. The treaty is due to expire in February 2021, unless both parties agree to extend it for no more than five years. New START provides the parties with 7 years to reduce their forces, and will remain in force for a total of 10 years."
CRS Report for Congress, R41219
Congressional Research Service: https://crsreports.congress.gov/