How many countries are considered to be nuclear-weapon states under the The Nuclear Threat Initiative (NPT)?

Correct Answer: B. 5

The five nuclear weapon states are China, France, Russia, the United Kingdom, and the United States.
NPT – The Nuclear Threat InitiativeThe NPT defines a nuclear-weapon state as a state that manufactured and exploded a nuclear weapon or other nuclear device before 1 January 1967. These states are China, France, Russia, the United Kingdom, and the United States. All other states are non-nuclear-weapon states under the Treaty. Other states that possess nuclear weapons are India, Pakistan, and North Korea. Since the NPT entered into force in 1970, these three states were not parties to the Treaty and have conducted overt nuclear tests. North Korea had been a party to the NPT but withdrew in 2003.