Russia has warned the American destroyer USS Donald Cook deployed in the Black Sea against approaching Russian coasts, stressing that Moscow is closely watching and monitoring the warship’s actions.

Visits to the Black Sea by US warships have nothing to do with US security and are motivated by domestic politics, said Russian senator Alexei Pushkov on Sunday.

“US warships are becoming frequent visitors to the Black Sea. These visits have nothing to do with US security,” Pushkov, a member of Russia’s Upper House Commission on Information Policy, wrote on his Twitter page.

“They flaunt their flag, send us a signal, and appease their own senators, who are demanding they send a whole military fleet to the Black Sea. They should keep away from our coastline,” he warned.

The US guided-missile destroyer Donald Cook began moving towards the Black Sea on Saturday, less than two weeks after another US Navy vessel was deployed there.

Earlier this month, the Whidbey Island-class dock landing ship USS Fort McHenry was deployed to the Black Sea where its crew trained with sailors from the Romanian Navy.

The US navy claims the USS Donald Cook seeks "to conduct maritime security operations and enhance regional maritime stability, combined readiness and naval capability.”

The Russian Black Sea fleet began monitoring the warship once it entered the region, RIA news agency cited Russia’s National Defense Control Center as saying on Saturday.

According to the Montreux international convention, the Arleigh Burke-class US warship can stay in the Black Sea for no more than 21 days, RIA cited the Russian defense control center as saying.

“Our arrival into the Black Sea will showcase the navy’s interoperability in pursuit of common security objectives, enabling us to respond effectively to future crises or deterring aggression,” Matthew J. Powel, commanding officer of the Donald Cook, said in a statement.

Six American military vessels carried out missions in the area in 2018, including the guided-missile destroyers USS Ross, USS Carney, and USS Porter, as well as the command ship USS Mount Whitney, the dock landing ship USS Oak Hill, and the expeditionary fast transport USNS Carson City.

The situation in the area remains tense after three Ukrainian Navy ships violated the Russian maritime border in the Kerch Strait, between Crimea and mainland Russia, on November 25.

The provocative actions of the Ukrainian vessels led to a lengthy chase and eventually prompted the Russian Coast Guard to use force to stop the perpetrators.

The incident, which occurred in an area that was Russian territorial waters even before reunification with Crimea in 2014, and ended in no fatalities, was quickly condemned by Washington as an act of “aggression” and led to the cancellation of a much-anticipated summit between Donald Trump and Vladimir Putin.