President Obama delivers a speech in Prague outlining his vision of a world free of nuclear weapons while promising to keep nuclear weapons as long as other countries do.
Russia announces a new nuclear doctrine in which they reserve "the right to use nuclear weapons in response to the use of nuclear and other weapons of mass destruction against it and its allies, as well as an aggression against the Russian Federation with the use of conventional weapons jeopardizing the very existence of the state."
The United States releases its 2010 Nuclear Posture Review, which will guide US nuclear decisions for years to come.
US President Barack Obama and Russian President Dmitry Medvedev sign the New START agreement to replace the expired Strategic Arms Reduction Treaty of 1991.
US President Barack Obama hosts a Nuclear Security Summit with the heads of state from 47 nations. The summit focused mainly on the threat of nuclear terrorism and the need to secure loose nuclear material.