Iran nuclear weapons map

Damaged cars that three Iranian scientists were riding in when they were killed in bombings over the last three years are displayed outside a conference hall hosting the meeting of Non-Aligned Movement, in Tehran, Iran, Aug. 26, 2012. Iran says the attacks against its scientists are part of a covert campaign by Israel and the West to sabotage its nuclear program, which the U.S. and its allies suspect is aimed at producing nuclear weapons.

President Bush discusses a National Intelligence Estimate that Iran halted its nuclear weapons program in 2003.

Billionaire Warren Buffett, pictured at a philanthropy press conference in Beijing on Sept. 30, 2010, has called the threat of nuclear weapons "the great problem of mankind"

A South Korean man protests the North’s defiant declaration that it has nuclear weapons

A South Korean protester smashes a mock atomic bomb during a rally against North Korea's suspected nuclear weapons program

DISARMING DISCUSSION: TIME's roundtable, which included former Soviet leader Gorbachev (third from left), agreed that greater cooperation between Washington and Moscow on nuclear weapons is vital