MOSCOW - Moscow will not be intimidated by US efforts to brandish its "nuclear sledgehammer", local media on Thursday cited Sergei Naryshkin, director of the Foreign Intelligence Service of Russia.

"The subcritical experiment conducted by the United States on May 14 this year at an underground laboratory for nuclear tests at a test site in the state of Nevada is rather concerning," TASS reported, citing Naryshkin.

READ MORE: Russia says defused unexploded munition near Kursk nuclear plant

"The experiment was not a full-scale nuclear test and does not formally violate the Comprehensive Nuclear Test Ban Treaty or the US moratorium on nuclear tests," he added.

However, Naryshkin noted, this test clearly illustrates US intensions, as it tries to flaunt its "nuclear sledgehammer", similar to how US President Harry Truman wanted to intimidate the leadership of the Soviet Union in 1945.

"It didn't work then, and it will not work now," he said, adding that "the lessons of World War II and the Cold War are forgotten by those for whom it is beneficial."

ALSO READ: Russian Navy inducts new Karakurt-class corvette

The US National Nuclear Security Administration announced earlier in May that it successfully conducted a subcritical experiment on May 14 at the PULSE underground facility at the Nevada National Security Site.