In a speech later on Tuesday, Raúl Castro used some his strongest anti-American language in months, thrashing Mr. Obama over the sanctions and any suggestion that détente would lead to political change on the island.

“The United States should understand once and for all that it is impossible to seduce or buy Cuba nor intimidate Venezuela,” he said. “Our unity is indestructible.”

Even before the meeting in Havana, State Department officials, who announced the meeting on Friday, had sought to play down expectations, saying it would be a roll-up-the-sleeves working session and would probably not include news media appearances.

The main hurdle for Cuba is its continued presence on the State Department’s list of nations said to support international terrorism. When Mr. Obama announced in December that the United States and Cuba would seek to restore normal relations, he suggested that it did not belong on the list and ordered a review. Cuba has also complained about its inability to find a bank for its diplomatic missions in the United States, in part because of the terrorism designation, which was made in 1982.

Most analysts view the removal of Cuba from the list as an easy call — it long ago renounced support for insurgencies — but the delay in any decision is causing speculation that the administration has not found a way to do it that would withstand a potential challenge from the Republican-controlled Congress.

Even if Mr. Obama were to authorize the removal of Cuba from the list, it would not come off it until after a 45-day grace period during which a joint resolution of the House and Senate could stymie the process. Taking that into consideration, Cuba would not be off the list before the summit meeting, though the administration’s position could be known.

This month, Spain asked the United States to help it get Cuba to extradite two fugitive members of a Basque separatist group. Although a State Department report in 2013 noted the repatriation of several members of the Basque group to Spain, Cuba’s decision to allow some members to stay on the island has been used in part to justify the terrorism-list designation.