THE HAGUE, Netherlands -- Japan will announce today that it will turn over to Washington more than 700 pounds of weapons-grade plutonium and a large quantity of highly enriched uranium, a decades-old research stockpile that is large enough to build dozens of nuclear weapons, according to U.S. and Japanese officials.
The announcement is the biggest single success in President Barack Obama's five-year-long push to secure the world's most dangerous materials, and will come as world leaders gather today for a nuclear security summit. Since Mr. Obama began these meetings with world leaders -- this will be the third -- 13 nations have eliminated their caches of nuclear materials and scores more have hardened security at their storage facilities to prevent theft by potential terrorists.
Japan's agreement to transfer the material -- the amount of highly enriched uranium has not been announced but is estimated at 450 pounds -- has both practical and political significance. For years, these stores of weapons-grade material were not a secret, but were lightly guarded at best; a reporter for The New York Times who visited the main storage site at Tokaimura in the early 1990s found unarmed guards and a site less-well protected than many banks. While security has improved, the stores have long been considered vulnerable.
Iran has cited Japan's large stockpiles of bomb-ready material as evidence of a double standard about which nations can be trusted. And last month, China began publicly denouncing Japan's supply, in apparent warning that a rightward, nationalistic turn in Japanese politics could result in the country seeking its own weapons.
At various moments, right-wing politicians in Japan have referred to the stockpile as a deterrent, suggesting that it was useful to have material so that the world knows Japan, with its advanced technological acumen, could easily fashion it into weapons.
The nuclear fuel being turned over to the United States, which is of American and British origin, is a fraction of Japan's overall stockpile. Japan has more than 9 tons of plutonium stored in various locations, and in the fall it is scheduled to open a new nuclear fuel plant that could produce many tons more every year. U.S. officials have been quietly pressing Japan to abandon the program, arguing that the material is insufficiently protected even though much of it is in a form that would be significantly more difficult to use in a weapon than the supplies being sent to the United States.