Russian President Vladimir Putin on Wednesday monitored drills of the country’s strategic nuclear forces involving multiple practice launches of ballistic and cruise missiles, the Kremlin said.

Russian Defense Minister Sergei Shoigu reported to Putin that the drills were intended to simulate a “massive nuclear strike” by Russia in retaliation for a nuclear attack on Russia. The exercise comes amid soaring Russia-West tensions over Moscow’s actions in Ukraine.

The Kremlin said in a statement that all tasks set for the exercise were fulfilled and all the missiles that were test-fired reached their designated targets.

Washington has said that Moscow informed it about the drills in advance.

The Russian exercise comes amid Moscow’s warnings of a purported Ukrainian plot to detonate a radioactive device commonly known as a “dirty bomb” in a false flag attack to blame Russia. Ukraine and its allies strongly reject the allegation.