The four Russian vessels arrived in Havana Harbor fresh from military exercises in the North Atlantic Ocean, Russia’s Defense Ministry said. They’re due to stay through Monday.

The ships aren’t carrying nuclear weapons, the Cuban and Russian foreign ministries have said, “so their stop in our country does not represent a threat to the region,” Havana said last week.

Here’s what you need to know.

Russia practiced launching high-precision missiles in the Atlantic after Biden said Ukraine could use U.S. weapons in Russia.

The Russian flotilla includes the frigate Admiral Gorshkov and the nuclear-powered submarine Kazan, a medium tanker and a rescue tugboat. Even without nuclear weapons, the frigate and the submarine are capable of launching Zircon hypersonic missiles, Kalibr cruise missiles and Onyx anti-ship missiles, Russia’s most highly touted modern weapons.

Several hours before entering the Havana harbor, Russian defense officials said, the flotilla completed an exercise in “the use of precision missile weapons.” Sailors used computer simulations to “hit” targets without launching actual missiles.

In Moscow, Russian Foreign Minister Sergei Lavrov met with his Cuban counterpart, Bruno Rodríguez Parrilla. Lavrov affirmed Russia’s “continued support for Havana in its just demand for a complete and immediate end” to Washington’s 62-year embargo on most trade with Cuba and the removal of the country from the State Department’s list of state sponsors of terrorism.

The visit came on Russia Day, when Russians mark the dissolution of the Soviet Union. State television highlighted extensive coverage of the event in the U.S. media, including clips from CNN. One Russian reporter described the visit as retaliation for Biden’s decision to allow Ukraine to strike inside Russia with American weapons.

“Last week, President Vladimir Putin made it clear that it reserves the right for a mirror response — that is, supplying long-range weapons to countries that feel the pressure of the United States,” the Russia 24 reporter said.

Cuba, mired in its worse economic crisis in years, is welcoming its longtime supporter.

Cubans lined the Havana waterfront Wednesday to see the Russian ships arrive. The Russians fired 21 salvos in honor of their hosts; the Cubans responded with an artillery salute from the San Carlos de La Cabaña Fortress.

Cuba’s foreign ministry said the visit reflects “the historical friendly relations” between Havana and Moscow, ties that go back to Soviet support for Cuba’s communist government and purchase of sugar, rum and other commodities. Cuba is currently mired in a dire economic crisis, including shortages of food, electricity and fuel, reminiscent of the so-called Special Period of the early 1990s, when the Soviet Union collapsed and support from Moscow sharply dropped.

Cuba emerged from years of deprivation with the support of Venezuela’s Hugo Chávez and improved relations with Russia under Putin. Lavrov said Wednesday that Moscow would continue to provide humanitarian support to Cuba.

The Russian foreign ministry thanked Cuba for its “principled position” on Ukraine. Rodríguez Parrilla, the Cuban foreign minister, said the country condemns “the increasingly aggressive stance of the U.S. government and NATO,” including sanctions against Russia.

Lavrov has been a frequent visitor to the region. He traveled in February to Venezuela, where he affirmed Russia’s support for the socialist government of Nicolás Maduro, Chavez’s successor. He stopped in Cuba during that trip also.

Cuban President Miguel Díaz-Canel visited Putin in Moscow in May.

The United States doesn’t see a threat, but is monitoring the visit.

The U.S. Defense Department has been tracking the Russian visit to Cuba since it was announced June 6. U.S. Navy and Coast Guard vessels are “going to continue to monitor,” Pentagon spokeswoman Sabrina Singh said Wednesday. ABC News reported that three U.S. Navy destroyers, a Coast Guard Cutter and Canadian and French frigates were keeping watch.

Singh said the Russian exercises didn’t pose a threat to the United States.

“This is not a surprise,” she said. Such “routine naval visits” by the Russians, she said, have occurred “during different administrations.”

A spokesman for U.S. Southern Command said the organization routinely monitors “activities of concern” nearby. Authorities anticipate that the Russian vessels might also visit Venezuela. Maduro’s government, also under heavy sanction by the United States, has scheduled a presidential election for July.

Retired Adm. Jim Stavridis, who headed Southern Command from 2006 to 2009, said naval deployments to the Caribbean are “long and difficult” for Russian forces, and provide “good practice for our forces, tracking and monitoring them.”

Putin is showing he ‘still has the ability to operate in the U.S. sphere of influence.’

Russian forces have made several visits to Cuba and Venezuela in recent decades. In 2018, Moscow sent two supersonic, nuclear-capable Tu-160 bombers to Venezuela for a brief stop. The next year, as the Trump administration stepped up efforts to oust Maduro, Russia dispatched 100 troops and equipment to Venezuela and signed an agreement allowing it to send ships.

Of course, the most famous Russian visit to the region came in 1962, when the U.S. discovery of Soviet missile sites in Cuba brought the world to the brink of nuclear Armageddon. President John F. Kennedy and Soviet Premier Nikita Khrushchev resolved the two-week Cuban missile crisis peacefully with an agreement that each side would withdraw missiles deployed near the other and that they would establish direct communications — the so-called red telephone — to forestall similar crises in the future.

Videos now of a Russian submarine arriving in Cuba, political scientist Vladimir Rouvinski said, help Moscow show that “efforts by the United States to diminish their presence everywhere, in particular in Latin America, are not working.”

“We have to see that Russia is not willing to abandon Latin America,” said Rouvinski, of Icesi University in Colombia, even as its military is consumed by Putin’s invasion of Ukraine.

Putin aims to signal that “he still has the ability to operate in the U.S. sphere of influence,” said Cynthia Arnson, a distinguished fellow at the Wilson Center’s Latin America Program.

The United States stages similar exercises near Russia and China.

The United States has a long history of deploying the Navy and other forces to demonstrate its range and capabilities in support of allies and against adversaries.

In May, the Destroyer USS Halsey conducted what the Navy called a “Freedom of Navigation Operation” to challenge “restrictions on innocent passage imposed by the People’s Republic of China (PRC), Taiwan, and Vietnam.”

A spokesperson for China’s Eastern Theater Command accused the United States of having “publicly hyped” the ship’s transit through the Taiwan Strait, the Associated Press reported. Chinese Navy Senior Capt. Li Xi said the command sent naval and air forces to monitor.

Last year, the destroyer USS Nitze and the amphibious command ship USS Mount Whitney made separate port calls to Istanbul on the Bosporus. That’s roughly 20 miles from the Black Sea, where Ukraine has used sea drones and missiles to attack a Russian fleet.