Four Russian naval vessels - including a nuclear-powered submarine and a frigate - have arrived in Cuba, in what is seen as a show of force amid tensions with the West over the war in Ukraine.
The vessels are anchored at the Havana Bay - some 90 miles (145km) from the US state of Florida.
Russia's defence ministry says the Admiral Gorshkov frigate and the Kazan submarine are both carriers of advanced weapons, including hypersonic missiles Zircon. They earlier conducted missile drills in the Atlantic.
But Cuba's foreign ministry says none of the vessels has nuclear arms on board, and their five-day visit does not pose a threat to the region.
US officials say they are closely monitoring the visit.
The US Navy also used sea drones to shadow the Russian vessels as they got close to Cuba, BBC's US partner CBS reports.
Early on a grey and overcast morning, the Russian vessels entered Havana Bay, flanked by smaller support vessels, to a 21-gun salute.
In a statement, Russia's defence minister said the visit was unofficial, allowing the vessels' crews to "rest and get acquainted with local attractions".
Russia has sent warships to Cuba in the past and the two nations are long-standing allies - but the timing of these particular exercises stands out.
Coming amid growing tensions over Russia's full-scale invasion of Ukraine in 2022, the operation is being interpreted by some as sabre-rattling by Moscow.
Certainly, it appears to send a pretty clear message from the Kremlin to Washington about what they consider to be meddling in their backyard.
The visit is an important symbol of support to the communist-run government in Cuba and its socialist ally, Venezuela, where the warships may sail to next after they finish in Havana.
From the US perspective, officials have indicated that they are aware of the visit - but do not consider that it poses a threat to the US, adding that their understanding was that the nuclear-powered submarine was not carrying nuclear weapons.
In essence, while the visit may be considered broadly routine, the context of wider global hostilities in which it is taking place is anything but.