Russian military exercises in the Caribbean: Here's what to expect

Three Russian ships and a nuclear-powered submarine are expected to arrive in Cuba this week ahead of military exercises in the Caribbean, officials said. While the exercises aren't considered a threat to the U.S., American ships have been deployed to shadow the Russians, U.S. officials told CBS News.

The Russian warships are expected to arrive in Havana on Wednesday and stay until next Monday, Cuba's Foreign Ministry said in a statement. A U.S. official told CBS News national security correspondent David Martin the U.S. intelligence community has assessed that the submarine in the group is nuclear powered but it isn't carrying nuclear weapons.

"We have no indication and no expectation that nuclear weapons will be at play here in these exercises or embarked on those vessels," White House national security spokesman John Kirby told CBS News senior White House and political correspondent Ed O'Keefe last week.