Russian sailors were seen standing on a nuclear-powered submarine as it entered Cuban waters Wednesday with three Russian naval ships.

The vessels are expected to stay in Havana through the weekend ahead of military exercises in the Caribbean in the coming weeks.

Photos taken in Havana showed the submarine, identified as the Kazan, cruising into the Cuban capital city’s harbor about 100 miles southwest of Key West, Florida.

The U.S. intelligence community assessed that while the submarine is nuclear powered, it isn’t carrying nuclear weapons, a U.S. official told CBS News national security correspondent David Martin.

Crowds were seen onshore watching small boats accompany the parade of ships into Havana’s harbor.

Cuba’s Foreign Ministry had identified the Russian ships as the frigate Admiral Gorshkov, the fleet oil tanker Pashin and the salvage tug Nikolai Chiker.

The Admiral Gorshkov was previously used to test Russia’s hypersonic cruise missiles, according to the Reuters news agency.

The Russian ships were shadowed by U.S. Navy ships as they made their way to the island nation, the U.S. official told Martin. The American shadowing will continue when the ships leave Havana, which is expected to be next week.

The ships’ arrival coincided with Cuban Foreign Minister Bruno Rodríguez’s meeting with Russian Foreign Minister Sergey Lavrov in Moscow.

White House national security spokesman John Kirby told CBS News that the Russians’ time in the Caribbean wasn’t expected to pose a threat to the U.S.

“Clearly this is them signaling their displeasure about what we’re doing for Ukraine,” Kirby told CBS News senior White House and political correspondent Ed O’Keefe last week.