Obama is talking with China about nuclear sanctions against Iran

Washington - (NBC) - A summit for nuclear proliferation is taking place in Washington, DC this week. Many of the world's major leaders will attend, but Israel is not because of recent events in the region.

"We think we can make enormous progress on this," said President Barack Obama as he met four foreign leaders Sunday, including South Africa, which gave up its nuclear program.

He'll sit down with five more Monday. The most critical is President Hu Jintao of China. The U.S. wants China to support sanctions against Iran.

Secretary of Defense Robert Gates said, "The Iranian government has to decide that its own security is better served by not having nuclear weapons than by having them."

Iran has been enriching uranium, for electricity, it says. North Korea is also a concern.

The world fears an atomic bomb could get into the hands of terrorists.

"The ramifications economically, politically and from a security perspective would be devastating," said President Obama.

President Obama says the 46 leaders at today's summit are coming with specific ideas on how to secure all the "loose nukes" out there.

Notably absent is Israel. Its Prime Minister pulled out fearing criticism from Muslim countries there.

Secretary of State Hillary Clinton said, "The Israeli government will be represented at a very high level and they share our deep concern about nuclear terrorism."

President Obama says so does the world.

Copyright 2010 NBC. All rights reserved.