Ukraine and the United States have formalized a deal to dispose of Ukraine's stockpile of weapons-grade plutonium.

Secretary of State Hillary Clinton and Ukrainian Foreign Minster Kostyantyn Gryshchenko signed the agreement Monday in New York.

Clinton called it a win-win for both countries, saying it provides benefits for the Ukrainian people and makes the world safer for everyone.

President Barack Obama and Ukrainian President Viktor Yanukovych announced the deal last year at a nuclear security summit.

Ukraine will transfer to Russia its stored plutonium, which could be used to build nuclear weapons.

In exchange, the United States will build a nuclear research facility in Ukraine. The laboratory will specialize in using low-enriched uranium in medical research for treating cancer and other diseases.