Just two days ahead of a second round of talks on restoring diplomatic ties frozen for five decades, Cuba and the United States staked out competing demands to ensure progress.
Cuban officials demanded that as a preliminary step to renewing relations, Washington must remove the island from its list of state sponsors of terrorism.
But a US official insisted the two issues should not be linked.
"It would be very easy to restore diplomatic relations if they would not link those two things … it's a delay of their own making, frankly," the senior State Department official told reporters.
A delegation from Cuba will meet with US counterparts on Friday at the State Department to resume negotiations after a first historic round held in Havana last month.
"This session will focus entirely on the restoration of diplomatic relations," the US official said, adding the session would start at 9:00 am (1400 GMT) and end in the afternoon with press conferences by both sides.
"We will focus on just what we need to do and get resolved to open embassies in each other's countries, or transition our interests sections to embassies," the official said, adding "both sides have an interest in doing that as quickly as possible."
Washington has insisted that American diplomats must be allowed to operate freely and meet with dissidents on the communist-run Caribbean island.
But Havana has remained wary.
And even Cuba's dissident community has had mixed feelings about US President Barack Obama's December agreement with Cuban leader Raul Castro to seek normal ties.
Some have praised the move while others worry too much was conceded to the communist regime without getting much in return.
Some observers believe that diplomatic ties could be restored before a Summit of the Americas in Panama in April, to be attended by Cuba for the first time in the history of the regional gathering. Obama is also due to attend.
Terror review moving forward
But Cuban Deputy Foreign Minister Gustavo Machin said opening the embassies before then would "depend on America."
"It would be a contradiction" if Havana were still on the US list of state sponsors — which has made access to the international banking system difficult for Cuba — he told Cuban reporters.
The State Department official said however that restoring ties and removing Cuba from the terror list, to which it was added in 1982, are "two separate processes."
A review ordered by Obama on whether to take Cuba off the blacklist was "moving forward as quickly as we can … but we don't think that should be linked to the restoration of diplomatic relations."
The recommendation will go to Obama, who will then have to notify Congress.
Everything depends "on how our counterparts come to the table prepared to get things done and whether they are comfortable with the things we need to run an embassy," the US official said.
The US delegation is to be led by Roberta Jacobson, the State Department's top official for Latin America, who last month became the highest-ranking US official to visit Cuba in 35 years.
She will sit down with Cuba's chief negotiator, Josefina Vidal.
