Weapon of mass destruction
The only country to have used a nuclear weapon in war is the United States, which dropped two atomic bombs on the Japanese cities of Hiroshima and Nagasaki during World War II. There are eight countries that have declared they possess nuclear weapons and are known to have tested a nuclear weapon, only five of which are members of the NPT. The eight are China, France, India, North Korea, Pakistan, Russia, the United Kingdom, and the United States.
Historical nuclear weapons stockpiles and nuclear tests by country
North Korea joined the nuclear club in 2006 or before. A United States Defense Intelligence Agency report from 1999 projected that both Iran and Iraq would join the nuclear club and have 10-20 nuclear weapons in 2020. However, it is worth pointing out that this report was written before the overthrow of Iraqi dictator Saddam Hussein and before information was released indicating that Iraq had already given up its nuclear weapons program. Even before the U.S. started the nuclear club in 1945, some states (most notably Germany) unsuccessfully attempted to build nuclear weapons.