While the US and Russia, the world’s two leading nuclear powers, set the stage for the global review of the main treaty on limiting the spread of nuclear weapons by announcing a pact to cut their arsenals, China, the number three power, kept a low profile.

Since signing the Nuclear Non-Proliferation Treaty in 1992, China has increasingly cooperated with non-proliferation efforts among the five recognised nuclear powers but despite the treaty’s joint commitment to disarmament, China is gradually upgrading its missiles and has been wary of signs that debate at the review conference underway in New York might turn on them.

“Although the US and Russia have some 20 to 30 times more nuclear weapons deployed than China and the Chinese have the moral argument on their side for now, China is probably the only country undertaking modernisation,” says Bates Gill, head of the Stockholm International Peace Research Institute.