Retired Cuban leader Fidel Castro broke his silence Monday on rapprochement with the United States, giving guarded approval to the process now under way to establish diplomatic ties between the two countries.

In a message Castro sent to the University Students Federation, he said: “Defending peace is the duty of everyone. Any peaceful or negotiated solution to the problems between the United States and the peoples or any people of Latin America that doesn’t imply force or the use of force should be treated in accordance with international norms and principles.

“We will always defend cooperation and friendship with all the peoples of the world, among them our political adversaries,” said Castro, 88, in a message that also recalled his own entrance to the University of Havana 70 years ago.

If he had to do it all over again, he said he would have chosen a scientific field.

But Castro, who retired in 2006 after falling ill and ceded power to his younger brother Raul, said he doesn’t have confidence in U.S. policy nor has he exchanged “a single word with them.”

Ever since Raul Castro and President Barack Obama announced Dec. 17 that the two countries planned to re-establish diplomatic relations after 53 years of isolation, there has been silence from Fidel Castro about his old nemesis.

But in his message, the elder Castro said, “The president of Cuba has taken the appropriate steps in agreement with the prerogatives and powers granted him by the National Assembly and Communist Party of Cuba.”

Previous attempts at reconciliation with Washington ultimately failed while Fidel Castro was at the helm.

In his message, the former Cuban leader also commented on the changes he has seen in his lifetime as the world has become smaller and more globalized.