The New START Treaty , which was signed in 2010, between the United States and Russian Federation will cap the strategic deployed nuclear arsenals of each country at 1,550 warheads, a nearly 75% reduction compared with the first START (Strategic Arms Reduction Treaty), which expired in 2009.
New START follows a series of similar treaties between the United States and Russia all with the goal of reducing nuclear weapons in both countries and, ultimately, lowering the global nuclear proliferation risk and increasing international security.
The last nuclear weapon in the current stockpile was produced in 1991. President George H.W. Bush instituted a moratorium on conducting underground nuclear tests in 1992. This moratorium has been renewed by each President since.
The Nuclear Posture Review  (NPR) Report, released April 6, 2010, is the first overarching look at U.S. nuclear strategy since the end of the Cold War. The NPR, a legislatively-mandated review that establishes U.S. nuclear policy, strategy, capabilities and force posture for the next five years to ten years, outlines the missions and capabilities for existing weapons.
The U.S. nuclear stockpile includes both active and inactive warheads. Active warheads include strategic and non-strategic weapons maintained in an operational, ready-for-use configuration, warheads that must be ready for possible deployment within a short timeframe. Inactive warheads are maintained in a non-operational status at depots.
Although the current number of nuclear weapons is classified, the Department of Defense released the historical stockpile quantities. As of September 30, 2009, the U.S. stockpile of nuclear weapons consisted of 5,113 warheads. This number represents an 84 percent reduction from the stockpile’s maximum (31,255) at the end of fiscal year 1967, and over a 75 percent reduction from its level (22,217) when the Berlin Wall fell in late 1989.