Colombia's main rebel group has said that it will halt its unilateral ceasefire this weekend, adding a dose of uncertainty even as peace talks to end the half-century-old conflict resumed in the Cuban capital.
The rebels' chief negotiator, Ivan Marquez, said on Monday there is no chance his group would reconsider its decision to abandon its two-month-old ceasefire, which the government has steadfastly refused to reciprocate.
Military operations are set to resume on Sunday.
"The unilateral ceasefire ... ends on January 20," said Marquez. "That's it."
While the move was expected, it raises the prospects that slow-moving negotiations in Havana could be derailed - or at least shaken - by bloodshed back home.
Both sides have issued statements in the past 24 hours calling on the other to move more quickly. Talks got underway on Monday behind closed doors at a Havana convention centre.
Marquez also outlined specific demands for agrarian reform, one of the main points of contention between the sides and the focus of the early rounds of talks.
The rebels also said they were studying proposals made by Colombian citizens at a forum held in December in Bogota.
Humberto de la Calle, the government's chief negotiator, said he too hoped the talks would gain traction. He said the government had "put forward concrete solutions to transform the countryside'', without giving any details.
De la Calle said the government was prepared to extend guarantees to the rebels that the agreements reached in Havana would be honoured, but only once the FARC agrees to end the fighting.
"There can be no politics of war in Colombia," he said.
"We came to Havana to discuss guarantees to create a democratic atmosphere, and to invite the FARC to be part of that democracy."
Talks began in October in Oslo, Norway, and continued the following month in Havana. Norway and Cuba are acting as guarantors for the negotiations, with diplomats present at the table.
De la Calle said the talks will go on for 11 days, followed by a three-day break, before resuming again. Colombian President Juan Manuel Santos has said the negotiations must bear fruit by November or he will walk away.
Several past efforts at peace have failed, though there is growing optimism both sides want to find common ground.
The rebels have seen their numbers dwindle in recent years due to an aggressive government military campaign, funded in part by the United States, although they insist they are still a potent force.
The FARC has been fighting the Colombian government since the 1960s.