Russian President Vladimir Putin has suspended a cooperative program that commits Russia and the United States to eliminating parts of their weapons-grade plutonium stocks.
A presidential decree made public on October 3 says the implementation of the U.S.-Russia Plutonium Management and Disposition Agreement (PMDA) must be put on hold, "due to Washington's unfriendly actions toward Russia."
The agreement, signed in 2000 after years of negotiations, has been considered a flagship of bilateral cooperation.
According to the deal, the two countries committed themselves to turn parts of their weapons-grade plutonium stockpiles into fuel for nuclear power plants and other non-weapon forms.
An amending protocol to the agreement that called on each side to dispose of 34 metric tons of plutonium came into force in 2011.
The two countries own the world's largest stockpiles of plutonium that can be used for nuclear weapons.
U.S.-Russian ties have plunged to levels of acrimony unseen since the end of the Cold War following Russia's military seizure of Ukraine's Crimean Peninsula in March 2014 and an ensuing war between Kyiv's forces and Russia-backed separatists that has killed more than 9,500 people.