Japan plans to turn over to the United States more than 315kg of weapons-grade plutonium and a supply of highlyenriched uranium, a move that could help allay China's concerns about the material being used for an atomic bomb.
US President Barack Obama and Japanese Prime Minister Shinzo Abe announced the plan yesterday at a nuclear security summit in the Netherlands.
"This effort involves the elimination of hundreds of kilograms of nuclear material, furthering our mutual goal of minimising stocks of [highly enriched uranium] and separated plutonium worldwide, which will help prevent unauthorised actors, criminals or terrorists from acquiring such materials," the leaders said in a joint statement released by the White House.
"This material, once securely transported to the United States, will be sent to a secure facility and fully converted into less sensitive forms."
The plutonium, they said, would be prepared for "final disposition".
The material designated for transfer to the US has been kept for decades at a research reactor site in Tokaimura, the site of a 1999 accident that killed two workers who mishandled a highly enriched uranium solution. More than 300 people were believed to have been exposed to radiation exceeding the annual limit after a nuclear chain reaction that lasted 20 hours.
China and Russia have expressed concerns about the size of Japan's plutonium holdings, which were estimated to be enough to make 50 nuclear bombs.
"Japan has stockpiled large volumes of sensitive nuclear materials, including not only plutonium but also uranium, and that's far exceeding its normal needs," Chinese foreign ministry spokesman Qin Gang said earlier this month.
Nuclear-armed China is involved in a bitter territorial dispute with Japan over islands in the East China Sea. Japan, the world's only target of atomic bombs, does not have nuclear weapons, and says it will not seek to obtain them.
"While Japan has no stated plan to use its nuclear fuel for a weapons programme, its ability to do so is causing mistrust among its neighbours," said Steve Fetter, the former assistant director in the White House's science and technology policy office.
"When you combine those things with disputes over island territories, I think it's easy for people in China to connect that this is another indication that Japan has other motives."
Despite its international pledge not to possess excess stock of plutonium, Japan has large amounts of the weapons-grade material. The amount to be returned to the US this time is a fraction of Japan's overall stockpile.
More than nine tons of separated plutonium are stockpiled in Japan, according to IAEA declarations. Another 35 tons are stored outside the country. Facilities in France and Britain currently reprocess Japanese spent fuel.
Yosuke Isozaki, a senior adviser to Abe, says the handing over of highly enriched uranium and plutonium is part of Japan's efforts to prevent proliferation and possible abuse of nuclear material by terrorists - the main aim of the Hague summit.
China's own nuclear weapons programme is thought to have left the country with as many as 75 nuclear-capable intercontinental ballistic missiles, according to US Department of Defence estimates cited by the Washington-based Nuclear Threat Initiative.
Associated Press, Bloomberg, Reuters