Russian President Vladimir Putin personally conducted the launch of four ballistic missiles as part of a training exercise of Russia’s nuclear forces, the Kremlin said on Friday, according to AP. The drills were conducted on Thursday where nuclear submarines, strategic bombers and a land-based launcher were test-fired.

“The commander in chief conducted the launch of four intercontinental ballistic missiles,” Putin spokesperson Dmitry Peskov said, adding that the training exercise was not connected with any international events.

In a statement, the Russian Defence Ministry said a Topol intercontinental ballistic missile had been test fired from the Plesetsk cosmodrome in northern Russia, which hit its designated target at the Kura firing range thousands of kilometres away, Reuters reported. Two other rockets were fired from nuclear submarines in the Pacific Ocean and Arctic Sea, it added.

The drills come amid escalating tensions between North Korea and the United States, after Pyongyang conducted its sixth and most powerful nuclear test in September.