NPT 101: Which countries have nuclear weapons?

Five signatories to the Non-Proliferation Treaty, or NPT, have nuclear weapons: the US, Russia, China, France, and Britain. Of those, the US and Russia control the vast majority of the world's nuclear warheads.

Yet three non-NPT members – Israel, India, and Pakistan – have all secretly developed nukes and suffered little consequence. North Korea, a former signatory, took advantage of a loophole in the treaty, pulling out in 2003 and testing nuclear weapons.

Iran, which Western powers suspect of developing nuclear weapons, lies at the nexus of the NPT’s declared rights and obligations, and will be a key talking point at the NPT Review Conference held May 3-28 in New York.

IN PICTURES: Nuclear Weapons

Iran says its nuclear programs aim to peacefully produce nuclear energy – an “inalienable right” enshrined in the NPT – and that nuclear weapons are forbidden by Islam. Yet India declared peaceful intentions, too – until it went nuclear in 1974.

“The [global] nonproliferation regime is at a very, very fragile point in its history,” says Natalie Goldring, a senior fellow at Georgetown University’s Center for Peace and Security Studies. “If Iran develops and deploys nuclear weapons, I don’t know if that is the tipping point, but I wouldn’t be incredibly surprised if it were.”

The NPT has seen a number of events undermine it in recent years.

Israel in 2007 attacked a facility in Syria it said was a budding nuclear plant, notes Ms. Goldring. Pakistan is also not an NPT member, but is under threat from Sunni militants, and could feel the need to boost its nuclear arsenal to match India – another non-NPT member that is nevertheless engaged in big-ticket deals with the US and other weapons states.

There is a “drip, drip, drip” erosion, Goldring says, a “debilitating effect on the [nonproliferation] regime with each of these announcements. It decreases the power of the regime for those who are inside, and decreases the incentives for those who are outside to want to be inside.”

Reversing that trend would be a critical achievement of this NPT conference in New York, though the last confab in 2005 ended in acrimony and without a final declaration.

Related:

NPT 101:

Part 1: How relevant is cold war treaty in age of terrorism?

Part 2: Which countries have nuclear weapons

Part 3: Why Iran sees nuclear 'hypocrisy

Part 4: Clash between nuclear haves and have-nots

Part 5: Is Iran violating the nuclear treaty?