All nuclear material on Russian territory is safely protected, says a Russian memorandum on nuclear security distributed at the Nuclear Security Summit in Washington on Tuesday.

"Nuclear security in Russia is appropriately maintained. The Russian Federation confirms that all nuclear materials on its territory and the corresponding installations are physically secured," the document says.

A plenary session of the 47-nation U.S. summit on nuclear security began on Monday. Discussions are taking place behind closed doors. The results of the talks will be announced during a news conference afterwards.

Russian Foreign Minister Sergei Lavrov and U.S. Secretary of State Hillary Clinton have signed a protocol to update the U.S.-Russian 2000 agreement on eliminating excess weapon-grade plutonium from defense programs. The agreement states that Russia and the U.S. will each dispose of 34 metric tons of excess weapon-grade plutonium.