Nuclear Threats

UNITED STATES Top dog in the nuclear pack, the U.S. set off the world's first bomb in 1945, and has done more testing since than the rest of the world combined. Under an international treaty, the U.S. stockpile, which is the world's largest, will dwindle to 3,500 deployed warheads by 2003. ARSENAL: 7,200 deployed warheads (Allies Britain and France have more than 600.)

RUSSIA The cold war superpower's stockpile has shrunk considerably--Moscow is aiming for 3,500 by 2003--and would be going faster if not for limited funds. All nuclear weapons stationed in Kazakhstan, Ukraine and Belarus have been returned. ARSENAL: 6,400 deployed warheads

CHINA The country maintains a bare-bones arsenal, but tucked deep in the mountains of central China are about 20 missiles capable of reaching the U.S. The rest could hit Japan, Russia or India. ARSENAL: Around 300 warheads

INDIA AND PAKISTAN New Delhi fought a losing war against Beijing in 1962, and a China nuke buildup would trigger an Indian response in kind, which in turn would trigger a Pakistani one. New Delhi and Islamabad, which have fought numerous wars, are believed to have 50 and 25 warheads, respectively.

OTHERS? North Korea may have enough plutonium for one or two warheads, although its missiles cannot yet hit the continental U.S. The Middle East, meanwhile, is full of nascent nuclear powers. Iraq could have warheads by 2010. Iran is believed to be on the brink of developing a warhead. And some observers believe Israel may already have a couple of hundred nuclear weapons.

Source: Arms Control Association; Center for Defense Information; Department of Defense