Japan will hand over hundreds of kilograms of weapons-grade uranium and plutonium to the United States as part of efforts to reduce global stockpiles of sensitive atomic material.
U.S. President Barack Obama and Japanese Prime Minister Shinzo Abe announced the deal Monday at a two-day nuclear security summit in The Hague.
In a joint statement, the leaders said all highly-enriched uranium and separated plutonium will be removed from the Fast Critical Assembly at the Japan Atomic Energy Agency.
"The material will be transported to the United States for conversion into proliferation-resistant forms," said U.S. Energy Secretary Ernest Moniz Monday in the Netherlands. He called the agreement a "very significant security pledge."
Japan's special nuclear adviser Yosuke Isozaki said removing the nuclear material will help lessen the risk of nuclear terrorism, a focus of the summit.
Japan received the nuclear material from the U.S. for research during the 1960s and is reported to have more than 300 kilograms of mostly weapons-grade plutonium.
The meeting in the Hague brings together delegations from 53 countries to discuss reducing and securing nuclear supplies.
Also Monday, officials said Italy and Belgium have transferred highly enriched uranium and plutonium to the United States. Italy reportedly removed some 20 kilograms of nuclear material, while Belgium is said to have turned over a "significant amount."