Top diplomats from the United States and Cuba held talks on the sidelines of the Summit of the Americas Thursday. The meeting was the highest-level contact between the two countries in over 50 years.

U.S. Secretary of State John Kerry met with Cuban Foreign Minister Bruno Rodriguez in a hotel in Panama City. The meeting lasted two hours, and though specifics of the discussion have not been released, U.S. officials said that the meeting went well.

"Secretary Kerry and Cuban Foreign Minister Rodriguez had a lengthy and very constructive discussion this evening. The two agreed they made progress and that we would continue to work to resolve outstanding issues," a senior State Department official said, according to Reuters.

The meeting was the latest step in a process started by the Dec. 17 announcement from U.S. President Barack Obama of a historic shift in the U.S.' policy towards Cuba.

The last meeting of such high-level representatives from the two countries took place in 1959, when Vice-President Richard Nixon met with Cuban leader Fidel Castro.

One of the key issues likely to have been discussed at the meeting is recommendation from the U.S. State Department to remove Cuba from a list of countries that sponsor terrorism.

A review by the department has recommended removing Cuba from the list, and Obama is expected to announce a decision on the matter in the coming days. Congress, however, could block any move to remove Cuba from the list.

Cuba's presence on the list of state sponsors of terrorism has been a major sticking point in relations between the longtime foes. If the detente between the two countries is to progress toward the eventual goal of restoring full diplomatic relations and opening embassies, the country will have to be removed from the list.

Cuba is one of four countries still on the U.S. list of countries accused of repeatedly supporting terrorism. The others are Iran, Sudan and Syria. It was first put on the list in 1982 for offering sanctuary to militant ETA Basque separatists and Colombian Farc rebels, according to the BBC.

Obama and Cuban President Raul Castro are attending the summit. Though the two leaders do not have any formal meetings scheduled, they are expected to interact on the sidelines of the summit, the Associated Press reported.

The two countries still face other diplomatic hurdles in their quest to normalize relations. Mark Weisbrot, director of the Washington-based Center for Economic and Policy Research think tank, told AFP that removing Cuba from the list would be "just the beginning" of efforts to normalize relations.