Cuban President Raul Castro has arrived in Moscow for the first such visit since the end of the Cold War.
Mr Castro, who officially took over as president from his brother, Fidel, in February 2008, has said he wants to expand ties with Russia.
Relations cooled after the Soviet Union collapsed in 1991 and the flow of trade and subsidies to Cuba ended.
But relations have warmed recently. Mr Castro's visit follows one to Havana by Russian President Dmitry Medvedev.
"Relations between Russia and Cuba are excellent and this visit will serve to strengthen ties between our countries," Mr Castro told the Russian Itar-Tass news agency ahead of his arrival.
Russia was the first country to send humanitarian aid to Cuba after two major hurricanes last year, and the two countries signed major trade deals in November ahead of the visit by Mr Medvedev.
In December, a group of Russian warships visited Havana during a tour of the Caribbean.
Mr Castro is to meet Mr Medvedev on Thursday and formal talks between the two sides are scheduled for Friday.
Russia has concrete economic interests in Cuba and a number of business deals are likely to be signed during Mr Castro's visit.
Russian oil firms are said to be keen to join international firms drilling off the Cuban coast for oil.