The Rokkasho reprocessing facility, based in Japan's northern Aomori prefecture, is capable of producing nine tons of weapons-usable plutonium annually, said Japanese officials and nuclear-industry experts, enough to build as many as 2, 000 bombs, although Japanese officials say their program is civilian.

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However, we cautioned him that we had low confidence that it was part of a nuclear weapons program, not because there was an alternative explanation that made much sense but simply because our body of knowledge on the other parts needed for such a program (like a reprocessing facility or weaponization work) was pretty thin.

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Still, a senior administration official confirmed Wednesday that there has been increased activity at the facility, including the restarting of generators to create steam for reprocessing.

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