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.
Taiwan and weapons of mass destruction
The development of nuclear weapons by the Republic of China has been a contentious issue, as it had been triggered by PRC's first nuclear test in 1964. The U.S., hoping to avoid escalating tensions in the Taiwan Strait, has continually opposed arming the Republic of China with nuclear weapons after 1979. Accordingly, the Republic of China adheres to the principles of the nuclear Non-Proliferation Treaty and has stated that it does not intend to produce nuclear weapons, on the official basis. Past nuclear research by the ROC makes it a "threshold" nuclear state.