At the closing session of the Nuclear Security Summit, President Obama discusses progress made at this year's summit toward improving nuclear security around the world, and lays out work to be done over the next two years, prior to the 2016 summit in Chicago. March 25, 2014.

President Obama's remarks from the Opening Plenary Session of the Nuclear Security Summit in Seoul.

President Obama takes questions from the media about nuclear security, non-proliferation and the threat of nuclear terrorism at the Nuclear Security Summit in Washington, DC. April 13, 2010.