U.S., China Agree to Pressure Iran on Nukes

The White House says President Barack Obama and Chinese President Hu Jintao are instructing their diplomats to work on potential sanctions to make clear to Iran the cost of continued nuclear defiance.

The two leaders met on the sidelines of a U.S.-hosted summit on nuclear proliferation Monday.

White House national security aide Jeff Bader sought to find common ground at their hour-long meeting. Bader said the Chinese were "prepared to work with us."

He called it another sign of international unity on the issue.

Mr. Obama's pledge to one day rid the world of nuclear weapons faces global realities this week as representatives from 47 countries try to craft an agreement on keeping nuclear weapons out of terrorist hands.

Sweeping or even bold new strategies were considered unlikely to emerge from the two-day gathering that began Monday. But Obama invited the swarm of world leaders as an important step to intensify global focus on one of the most serious nuclear proliferation threats: a world in which non-state actors - like the al Qaeda terrorist organization - obtain nuclear materials.

More on Obama's nuclear strategy:

Obama Signs Nuclear Arms Pact with Russia
Read the Treaty
A Layman's Guide to the Nuclear Posture Review
Nuclear Posture Review Report(PDF)
Obama Hails Treaty as Mend to Russia Relationship

"The single biggest threat to U.S. security, both short-term, medium-term and long-term, would be the possibility of a terrorist organization obtaining a nuclear weapon. This is something that could change the security landscape in this country and around the world for years to come," Obama said as he conducted a series of bilateral meetings with world leaders Sunday.

"We know that organizations like al Qaeda are in the process of trying to secure nuclear weapons or other weapons of mass destruction, and would have no compunction at using them," Obama said.

The president has set a goal of ensuring all nuclear materials worldwide are secured from theft or diversion within four years. Analysts say meeting that ambitious goal is unlikely, reports CBS News correspondent Sharyl Attkisson, but this week's summit is viewed as a key milestone along the way.

List of World Leaders Attending the Summit
Analysis: Obama Seeks Legacy on Reducing World's Nukes

CBS News senior White House correspondent Bill Plante reports there are an estimated 3.5 million pounds of highly enriched uranium scattered across 40 countries, and just 55 pounds of the substance is sufficient to make a small nuclear device.

While the president's goal of eradicating that threat within four years is lofty, Sharon Squassoni, a Senior Fellow at the Center for Strategic and International Studies tells CBS News it might not be completely unattainable.

"Locking down all of this material in four years is a tough goal... but if all of these states - and some of them really do have nuclear security problems - if they really commit to working on it, I think it's achievable," said Squassoni.