Russian forces have conducted an exercise in the Baltic Sea, including drills to repel an underwater attack, the defense ministry said on Friday.

Units of divers "demonstrated skills in detecting and capturing a group of underwater saboteurs, as well as using FPV (first person view) drones to destroy unmanned boats of a mock enemy," the ministry said.

The drills were aimed partly at assessing the navy's anti-submarine sabotage defense units, it said.

It was the second time this month that Russia has held naval exercises with an anti-submarine component, after President Donald Trump said on Aug. 1 he had ordered two U.S. nuclear subs to take up positions closer to Russia.

In the first week of August, the Russian and Chinese navies practiced hunting and destroying an enemy submarine in the Sea of Japan.

The defense ministry published video of Russian Navy Commander Admiral Alexander Moiseyev inspecting the Baltic exercise, which also included a drill to protect an airfield from enemy drone strikes.