Cuban President Raúl Castro told the U.N. on Monday that normalizing relations with the U.S. will only occur once Washington returns the U.S. naval base at Guantánamo and lifts its trade embargo with the communist nation.

Since the efforts to normalize relations between the United States and Cuba were initiated last December, the U.S. has reopened its embassy in Havana, and Cuban medical researchers have begun to share their cancer studies with U.S. doctors. But, according to the Cuban leader, there is still a long way to go.

As Reuters reports, Castro insisted the people of Cuba be compensated for over 50 years spent under an American embargo.

"Now, a long and complex process begins toward the normalization of relations that will only be achieved with the end of the economic, commercial and financial blockade," he said, recognizing the difficulty involved in the task.

When it comes to lifting the trade embargo, U.S. President Barack Obama sides with Castro and said he is confident the U.S. Congress will lift what he calls "an embargo that should not be in place anymore.”

The trade embargo has been in place since 1960, and many Republicans in Congress want it to stay in place.

The United Nations General Assembly is scheduled to vote next month on a resolution demanding an end to the U.S. economic embargo against Cuba. Republican Sen. Marco Rubio released an open letter on Tuesday to Obama, in which he cautions the president against abstaining from the original U.S. resolution in the symbolic vote.

“Regardless of your beliefs, the U.S. embargo toward Cuba is codified in U.S. law and the reasons that it was imposed, including the Cuban government’s theft of billions of dollars of private property, remain unaddressed by Havana,” Rubio wrote. “Any disagreements over this law, which only regulates transactions by U.S. persons, should be debated in the United States Congress -- not at the United Nations General Assembly.”