A Russian intelligence warship, Viktor Leonov CCB-175, docked in Havana on Tuesday, one day ahead of the first official diplomatic negotiations between the United States and Cuba.
The ship's presence was not officially announced by Cuba, but US defence officials said it's not alarming.
There is a crew of about 200 in the intelligence ship, which also made unannounced docks in last February and March in Havana – formerly a close ally of Soviet Russia.
Meanwhile, a US delegation appointed by President Barak Obama has flown across the mere 101 miles of water separating Florida's Key West from Havana – the first American visit since 1980.
Led by Roberta Jacobson, US assistant secretary for Western hemisphere affairs, the delegation is set for a two-day discussion with Cuban officials. The ongoing talks will focus on immigration and restoration of diplomatic ties, a plan announced on 17 December by both President Obama and Cuban President Raul Castro.
The diplomats arrived in Havana earlier this week, stepping off a bus just blocks away from the National Capitol Building. The building looks strikingly similar to the US Capitol, with its Doric columns and large, neoclassical dome, though it hasn't been used as a seat of government since the Cuban Revolution in 1959.
Cubans hope for an end to the economic embargo, which costs the country an estimated $685 million annually. They also want to be scratched off the U.S. list of state sponsors of terrorism.
The Cuban government also opposes US laws which provide amnesty for any Cuban expatriates who find their way to American shores. US policy considers these individuals refugees, while Cuba says that such a policy encourages its citizens to make dangerous, ill-prepared trips across the waters of the Florida Current.
During his State of the Union address Tuesday night, President Obama said, ''We are ending a policy that was long past its expiration date.'' The line was directed at Congressional Republicans, who will likely oppose many aspects of the president's new policies.
While diplomatic relations can be restored by the president, embargos fall under congressional jurisdiction. If relations between the two nations are to be fully reconciled, Obama has to convince the new Republican majority to play ball.
Republicans have already criticized the president's decision, saying the new policy would effectively abandon Cuban opposition groups supported by the US.
But with the presence of the Russian spy ship, the approaching debate over the new US relationship with its Communist neighbour may extend beyond domestic politics.
A Cuban foreign ministry official stressed that improving ties with the US could be a long process.
''Cuba isn't normalizing relations with the United States,'' the official told reporters. ''Cuba is re-establishing diplomatic relations with the United States. The normalization of relations is a much longer process and much more complicated process.''