Russia has suspended another nuclear agreement with the United States, this one on working together to conduct nuclear energy research.
Underscoring how tensions between Washington and Moscow have deteriorated this week amid tit-for-tat suspensions of previous joint efforts, an announcement of the nuclear research suspension on October 5 described it as a "countermeasure" to U.S. sanctions imposed over Russia's aggression in Ukraine.
"We can no longer trust Washington in such a sensitive area as the modernization and security of Russian nuclear facilities," the Russian Foreign Ministry said, adding the agreement would only be reinstated if the United States lifts its sanctions.
Russian Deputy Foreign Minister Sergei Ryabkov told Interfax thatthe suspension of the 2013 research accord was a response to Washington's "hostile" move to suspend all such nuclear energy cooperation when it imposed the sanctions in 2014 after Russia forcibly annexed Ukraine's Crimea peninsula.
"So, the ball is fully in the U.S. court. We have just balanced from the legal point of view the things that Americans did in 2014," he said.
The impact of the move is likely to be less serious than Russia's suspension on October 3 of an agreement on disposal of weapons-grade plutonium. That agreement had been seen as a symbol of U.S.-Russian rapprochement after the Cold War.
The strain in Moscow-Washington relations has intensified rapidly since the United States suspended a joint effort with Russia to negotiate a cease-fire agreement in Syria over the weekend.
Since then, Russia has suspended several agreements with the United States and bolstered its forces in Syria as the Syrian Army stepped up its campaign -- with Russian backing -- to retake the city of Aleppo with a vicious bombing campaign.
U.S. State Department spokesman Mark Toner said the United States "regrets the Russian decision to unilaterally suspend cooperation on what we believe is a very important issue that's in the interests of both our countries."
With reporting by Reuters, AP, TASS, and Interfax