Geopolitics › Global issues & flashpoints › Nuclear weapons and proliferation
Nuclear Non-Proliferation Treaty (NPT)
Signed 1968; in force 1970; 191 parties· Treaty or event
FactTreaties, membership, measured data, events.
The 1968 treaty, with 191 parties, in which most nations forgo nuclear weapons and five recognized nuclear states pledge to pursue disarmament.
See it on the Geopolitics map →The picture
It recognizes five nuclear-weapon states, those that tested before 1967: the US, Russia, Britain, France and China. Others promise not to build weapons and accept IAEA inspections, in return for help with civilian nuclear power. Article VI commits all parties to negotiate disarmament. It was extended indefinitely in 1995. India, Pakistan, Israel and South Sudan never joined; North Korea withdrew in 2003. Review conferences in 2015 and 2022 ended without an agreed outcome.
Why it matters
In 1963 President Kennedy warned that 15 to 25 nations might soon have the bomb; there are nine. Most analysts credit the NPT, plus US alliances.
Key facts and numbers
The treaty text, UN Office for Disarmament Affairs membership records, IAEA safeguards reports and review-conference documents.
What to watch
Whether non-nuclear states keep faith while nuclear powers expand rather than disarm, and whether US allies such as South Korea, where polls favor a bomb, stay inside.
Connections (4)
▸Nuclear Non-Proliferation Treaty (NPT) aims to stop the spread of Nuclear weapons and proliferationFact
The relationship
The NPT is the main legal barrier to proliferation: non-nuclear members accept IAEA inspections and forgo weapons, while the five recognized nuclear states pledge disarmament talks. It has held most countries back, and in the 1990s South Africa, Ukraine, Belarus and Kazakhstan gave up weapons and joined as non-nuclear states.
Since when and why
Opened for signature on July 1, 1968, in force from March 5, 1970, extended indefinitely in 1995; review conferences every five years.
How we know
Membership records, IAEA safeguards reports, and the small number of nuclear states compared with 1960s predictions of many more.
What to watch
Whether a withdrawal by Iran, which has debated leaving, would trigger others in the Middle East, and whether the bargain holds as nuclear states expand.
▸North Korea (DPRK) withdrew in 2003 from Nuclear Non-Proliferation Treaty (NPT)Fact
The relationship
North Korea joined the NPT in 1985, threatened to leave in 1993, then announced its withdrawal in January 2003 after the US accused it of secret uranium enrichment. Free of treaty inspections, it tested its first nuclear device in 2006 and five more by 2017.
Since when and why
Joined December 1985; withdrawal announced January 10, 2003; tests in 2006, 2009, 2013, 2016 (twice) and 2017.
How we know
IAEA records, UN Security Council resolutions after each test, and seismic readings from the test site.
What to watch
Disputed: some states question whether the withdrawal was legally valid; North Korea is the only state ever to leave the treaty.
▸Iran is debating withdrawal from Nuclear Non-Proliferation Treaty (NPT)Fact
The relationship
Iran joined the NPT in 1970, which bars it from building nuclear weapons and requires IAEA inspections. After the 2025 strikes it curbed inspector access, and hardline lawmakers filed bills in March and September 2026 to quit, which takes three months' notice. The government says it still rejects nuclear weapons.
Since when and why
Iran's parliament in Tehran; bills filed on March 28 and in mid-September 2026, after the IAEA board referred Iran to the UN Security Council on September 9.
How we know
Iranian parliamentary records, President Pezeshkian's statements and IAEA board resolutions. Only North Korea has ever left the treaty.
What to watch
Unclear whether parliament has the votes (one MP predicted no more than 70) and whether Mojtaba Khamenei would approve leaving, which his father had opposed.
▸India never signed Nuclear Non-Proliferation Treaty (NPT)Fact
The relationship
India refused to sign the NPT, calling it discriminatory because it lets only five states, those that tested before 1967, keep nuclear weapons. It tested in 1974 and 1998 and has about 180 warheads. A 2008 US–India deal and a waiver from the Nuclear Suppliers Group let it buy civilian nuclear technology anyway.
Since when and why
Treaty opened in 1968; India tested at Pokhran in 1974 and May 1998, and Pakistan tested weeks later; the suppliers' waiver came in September 2008.
How we know
Indian government statements, the NPT text, SIPRI warhead estimates and the 2008 US–India civil nuclear agreement.
What to watch
Whether India's no-first-use pledge would hold in war, and whether China keeps blocking India's bid to join the Nuclear Suppliers Group.