And we've launched an effort to secure all loose nuclear materials within four years.

WHITEHOUSE: President Obama: Our Security, Our Values

The United States and Russia have a history already, a decade-long history, of locking down loose nuclear materials.

WHITEHOUSE: Signing of New START Nuclear Arms Treaty with Russia

We also discussed the fact that Russia has cooperated with us on critical issues to our national security like Iran sanctions, transit to supply our troops in Afghanistan, working on securing loose nuclear materials.

WHITEHOUSE: President Obama Meets with General Colin Powell

As nuclear powers, we can be full partners in preventing the spread of the world's most deadly weapons, securing loose nuclear materials from terrorists, and pursuing our shared vision of a world without nuclear weapons.

WHITEHOUSE: President Obama Welcomes Prime Minister Singh of India

He has focused very aggressively the fight against al Qaeda, as you know, and he has focused and his entire administration has focused on working with the 50 nations who are a party of the summit on the issue of securing loose nuclear materials and preventing them from getting into the hands of terrorists.

WHITEHOUSE: Press Briefing