A US Navy submarine has docked in Guantanamo Bay, Cuba, coinciding with a fleet of Russian warships assembling for planned military exercises in the Caribbean.

US Southern Command reported that the USS Helena, a nuclear-powered submarine, arrived in the waters near the US base in Cuba on Thursday. This occurred just a day after a Russian frigate, a nuclear-powered submarine, an oil tanker, and a rescue tug entered Havana Bay following drills in the Atlantic Ocean.

The stop is part of a “routine port visit” as the submarine travels through Southern Command’s region, the command stated in a social media post.

Other US ships have been tracking and monitoring the Russian drills, which Pentagon officials say do not pose a threat to the United States.

“This is not a surprise. We’ve seen them do these types of port calls before,” Pentagon spokesperson Sabrina Singh said on Wednesday when asked about the Russian drills. “We of course take it seriously, but these exercises don’t pose a threat to the United States.”

However, the exercises come less than two weeks after President Joe Biden authorized Ukraine to use US-provided weapons to strike inside Russia. In response, Russian President Vladimir Putin suggested that his military could take "asymmetrical steps" elsewhere in the world.

Russian nuclear-powered submarine in Havana

The Russian nuclear-powered submarine, Kazan, alongside other naval vessels, arrived in Cuba as part of a formerly announced five-day visit to Havana on June 12. 

According to Cuba, the Russian submarine was not carrying nuclear weapons and was accompanied by the frigate Admiral Gorshkov, as well as an oil tanker and a salvage tug.

Prior to entering the port in Havana, the fleet issued a statement saying it "completed an exercise on the use of high-precision missile weapons." Moreover, the Russian Defense Ministry noted that "In the coming days, the crews of the ships and support vessels will take part in a number of protocol events."

In parallel, during a meeting between Cuba's Foreign Minister Bruno Rodriguez and his Russian counterpart Sergey Lavrov, the former expressed Havana's "rejection of the expansion of the North Atlantic Treaty Organization (NATO) towards the Russian border," adding that it "led to the current conflict in Europe, and especially between Moscow and Kiev."