This State Department report assesses U.S. adherence to arms control, nonproliferation, and disarmament agreements, as well as an assessment of the adherence of other nations to such conventions, regimes, and treaties, including the Missile Technology Control Regime, Biological and Toxin Weapons Convention, Treaty on Open Skies, Nuclear Nonproliferation Treaty, and the Chemical Weapons Convention to name a few. Part I discusses U.S. compliance with arms control agreements. Part II discuses compliance by Russia and other successor states of the Soviet Union with treaties and agreements that the U.S. concluded with the Soviet Union. Part III informs on compliance by other countries that are parties to multilateral agreements with the U.S. Part IV discusses compliance with less formal agreements that have significant bearing upon arms control, nonproliferation, and/or disarmament issues. The issues addressed in this Report primarily reflect actions from January 1, 2009 through December 31, 2010.