Japan will turn over more than 700 pounds of weapons-grade plutonium and highly-enriched uranium to the United States, the two nations announced on the eve of an international security summit Monday at The Hague.

The stockpile, maintained by Japan for research purposes, will be securely transported to the U.S., where it will be converted into “less sensitive forms,” according to a joint statement. [READ THE STATEMENT HERE.]

“This pledge complements the significant role that both Japan and the United States are playing in finding new ways to continue improving global nuclear security,” leaders from the nations said, adding that move would “help prevent unauthorized actors, criminals, or terrorists from acquiring such materials.”

Japan will also convert its Fast Critical Assembly research facility so that scientific work could continue without the need for highly enriched uranium, which can be weaponized.

“The FCA will become the world’s first major fast critical facility to convert from HEU [highly enriched uranium] and separated plutonium fuels, marking a significant milestone for global nuclear security,” the White House said in a statement.

The deal is a significant victory for President Obama, who has made securing nuclear materials across the globe a major priority in his national security portfolio.

But according to The New York Times, which first reported the deal, the fuel being turned over to the U.S. represents only a fraction of Japan’s overall stockpile. According to the paper, Japan had more than nine tons of plutonium in locations around the country, and plans to open a new nuclear fuel plant that could increase that amount.