Secretary of State John Kerry warns (yawns) North Korea Tuesday that it won't tolerate its nuclear weapons.
Brooks Kraft / Corbis for TIME
President Bush discusses a National Intelligence Estimate that Iran halted its nuclear weapons program in 2003.
CHUNG SUNG JUN / GETTY
A South Korean man protests the North’s defiant declaration that it has nuclear weapons
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 protester smashes a mock atomic bomb during a rally against North Korea's suspected nuclear weapons program
Vahid Salemi / AP
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.
Photograph for TIME by Kathryn Cook / Agence VU
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