On Friday the American flag was raised in the U.S. Embassy in Cuba for the first time in 54 years, signaling the beginning of the end of icy relations between the two ideologically opposed nations.

Despite the optimism enthused by Secretary of State John Kerry, who, as reported by CNN, thanked the witnessing crowd and called the event a “truly historic moment,” there remains much work to be done in easing tensions between two counties that share over 50 years of strained relations.

A major bone of contention between the neighboring nations is Guantanamo Bay. Cuba wants back the land that is being used as a U.S. military detention camp, while Obama's administration has been clear that Guantanamo is not up for discussion.

Josefina Vidal, the director of U.S. affairs for Cuba's foreign ministry, is blunt about the delicate diplomatic work to come. Assuring Reuters that she would prefer not to be pessimistic, Vidal believes that Cuba will not give up anything just to ease congressional opponents of Obama or the anti-Castro exiles living Miami.

"No matter what we do or stop doing, these people ... are just going to ask for more and more and more," she said, adding, "They don't what what's good for the Cuban people. They want revenge."

One of the most vocal opponents to Obama’s attempts at restoring relations with the Cuban government has been Florida Sen. Marco Rubio. Denouncing the reopening of the U.S. Embassy is Havana, Rubio said, "As a symbol of just how backward this policy shift has turned out to be, no Cuban dissidents have been invited to today's official flag-raising ceremony at the U.S. Embassy in Havana."

“Their exclusion from this event has ensured it will be little more than a propaganda rally for the Castro regime," said Rubio.