Two British ships arrived in eastern Japan on Monday to transport a shipment of plutonium - enough to make dozens of atomic bombs - to the US for storage under a bilateral agreement.
The ships arrived at the coastal village of Tokai, northeast of Tokyo, home to the country's main nuclear research facility, the Japan Atomic and Energy Agency, according to Kyodo News and citizens' groups. It will take several hours to load the plutonium-filled casks on to the ships, both fitted with naval guns and other protection.
The Pacific Egret and Pacific Heron, both operated by Pacific Nuclear Transport, will take the 730 pounds of plutonium to the Savannah River Site, an American government facility in South Carolina under a pledge made by Japan in 2014. The plutonium, mostly from the US and some from France originally, had been used for research purposes.
Environmentalists said it was the largest such shipment since 1992.
Japan has accumulated a massive stockpile of plutonium - 11 metric tons in Japan and another 36 tons that have been reprocessed in Britain and France and are waiting to be returned to Japan - enough to make nearly 6,000 atomic bombs.
The latest shipment comes just ahead of a nuclear security summit in Washington later this month, and is seen as a step to showcase both countries' nuclear non-proliferation efforts.
Washington has increasingly voiced concerns about the nuclear spent-fuel-reprocessing plans by Japan and China to produce plutonium for energy generation, a technology South Korea also wants to acquire, saying they pose security and proliferation risks.
