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.
Nuclear terrorism
Nuclear weapons expert David Albright and author of "Peddling Peril" has also expressed concerns that Pakistan's stockpile may not be secure despite assurances by both Pakistan and U.S. government. He stated that Pakistan "has had many leaks from its program of classified information and sensitive nuclear equipment, and so you have to worry that it could be acquired in Pakistan". In 2015, Richard G. Olson, former US Ambassador to Pakistan, expressed confidence in the capabilities of the Pakistani security forces to control and
secure its nuclear weapons. He added that Islamabad has "specifically taken into account the insider threat".