Russia has reacted angrily to an assertion by a top U.S. defense official that Moscow "probably" violated an international nuclear test ban treaty.
The assertion is a "crude provocation," the Russian Foreign Ministry said in a statement on May 30.
The statement comes the day after the head of the U.S. Defense Intelligence Agency suggested that Moscow wasn't adhering to the 1996 Comprehensive Nuclear Test Ban Treaty (CTBT) and was likely conducting zero-yield nuclear tests.
"The United States believes that Russia probably is not adhering to its nuclear testing moratorium in a manner consistent with the 'zero-yield' standard," Lieutenant General Robert Ashley said in a speech in Washington.
Russia's Foreign Ministry said that "such accusations are absolutely groundless and aimed at trying again to smear our country."
It also called on the United States “to show a responsible approach and to ratify the [CTBT], without which it is impossible for it to come into force."
The agreement bans all nuclear explosions, either military or civilian, in any type of situation. It’s been signed and ratified by Russia, and signed by the United States, but not ratified.
It has not come into force globally, lacking the signatures from eight nuclear technology nations.
The dispute is one of several nuclear-related treaties that Moscow and Washington are at odds over.
Others include the Intermediate-Range Nuclear Forces Treaty and the Open Skies Treaty.
The two countries are also holding internal discussions about whether to extend the New START treaty, which expires in 2021.