sabre-rattling by Moscow

Russian warships leave Cuba after five days

The vessels, which included a nuclear-powered submarine and a frigate,
had been anchored at Havana Bay - some 90 miles (145km) from the US
state of Florida.

The US said it did not see the visit as a threat but added that it was
monitoring the vessels closely.

Following the fleet's arrival, the US docked a submarine, the USS
Helena, at its Guantanamo Bay Naval Base in Cuba on Thursday.

https://www.bbc.com/news/articles/ckrr8dn238yo