The U.S. and Japan said Monday that Japan would turn over hundreds of kilograms of nuclear material to U.S. custody, part of nuclear-security measures being announced at a summit in the Netherlands.

The plutonium and highly enriched uranium are currently held by the Japan Atomic Energy Agency at a facility in Tokai, north of Tokyo. In a joint statement, the countries said the material would be sent to a secure facility in the U.S. and converted into less sensitive forms.

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