"Equipment and personnel of the Baltic Fleet constantly keep track of actions of the US Navy's Ross destroyer that entered the waters of the Baltic Sea on 13 September 2020", the National Defence Management Centre said in a statement.
On 7 September, a NATO sea force led by Ross entered the Barents Sea, where it was tracked by the Northern Fleet.
The announcement comes amid intensified NATO intelligence activity near the Russian border. NATO spy aircraft have been detected almost daily in the airspace over either the Barents Sea or the Black Sea over the past month.
Moscow has warned that such regular flights by US and NATO aircraft near Russia's border poses the risk of accidental escalation. By comparison, Russian jets and bombers operate near US borders far less frequently, and typically stay at least 30 km away from the US border.