The left-wing leaders of Bolivia, Cuba and Venezuela have signed a three-way trade agreement aimed at countering US influence in Latin America.
Socialist presidents of Latin America unite
The pact was signed in Cuba by Bolivian President Evo Morales, Hugo Chavez of Venezuela, and their host Fidel Castro.
The initiative, the Bolivarian Alternative for the Americas, was drawn up by Cuba and Venezuela.
Mr Morales, an ally of both Mr Castro and Mr Chavez, decided to join it after his election last December.
The initiative - known by its Spanish acronym Alba - is being promoted as a socialist alternative to the Washington-backed Free Trade Area of the Americas.
The deal aims to reduce or eliminate tariffs between the three countries. But apart from this, it is very unlike conventional trade agreements, the BBC's Stephen Gibbs in Havana says.
Participants have vowed to work towards the eradication of illiteracy and the expansion of employment.
Cuba has promised to help Bolivia provide free eye treatment to those Bolivians who otherwise would not be able to afford it.
Venezuela has agreed to provide at preferential rates all the subsidised oil Bolivia requires for its domestic consumption.
Our correspondent says closer integration between oil-rich Venezuela and gas-rich Bolivia will give the new pact added weight.
The question now is who else they can persuade to join, he adds.
After the signing, Fidel Castro said: "Now, for the first time, there are three of us - I believe that, one day, all [Latin American] countries can be here."
After his arrival in Cuba on Friday, Mr Morales said the meeting was a was a "historic gathering of three generations and three revolutions".
Mr Chavez has vowed to create economic and political unity in South America without the help of Washington.
Earlier this month he took Venezuela out of the South American trade bloc, the Andean Community of Nations, saying it was overly aligned with the US.