Obama assembled a 47-nation summit to focus on nuclear terrorism in a post-Cold War world. After discussions that yielded few specifics, they reached a general agreement to secure all unaccounted-for nuclear material within four years.

Speaking only a few hours after North Korea launched a test missile, Obama underscored his commitment to ensuring safe use of nuclear power around the world.

In Prague, toward the end of his first overseas trip as president, Obama announced the U.S. will host a global summit on nuclear security within the next year to make sure international agreements, such as the Proliferation Security Initiative and the Global Initiative to Combat Nuclear Terrorism, are developed into “durable” institutions. He also called on countries to squash the “dangerous trade” of nuclear material by breaking up black markets, and detecting and intercepting materials in transit.

"We will set new standards, expand our cooperation with Russia, and pursue new partnerships to lock down these sensitive materials," Obama said.

The administration's budget outline for FY2010 slashes funding for the controversial nuclear waste disposal site at Yucca Mountain in Arizona. With no alternative proposed yet, this means that spent nuclear fuel will have to continue being stored on-site at nuclear reactors around the country.