BOGOTA: Colombian leftist rebels faced on Monday a new deadline for striking a peace deal with the government after President Juan Manuel Santos warned they have less than a year to reach a negotiated end to Latin America’s longest-running insurgency.

The warning on peace talks came after the Colombian military launched a new operation against the FARC rebels at the weekend, in which it said at least 20 rebels were killed.

“This has to be a process of months, rather than years. In other words, this should not last any longer than November next year at the latest,” the president said at an event in the Caribbean resort city of Cartagena.

“But it is important to be patient, and not demand immediate results, because... some very complicated issues are being discussed.” However, Santos did not specify what will happen if the newly-imposed deadline is not met.

The Revolutionary Armed Forces of Colombia (FARC), Latin America’s longest running insurgency, started talks formally with Bogota on Oct. 18 in neutral Norway.

The talks moved to Havana on Nov. 19 and will resume this week.

It is a conflict that has dragged on for almost a half century, with some 600,000 dead, 15,000 missing and four million people domestically displaced.

On last Thursday, Colombian government and rebel negotiators reported progress in the first peace talks in a decade.

On the delicate process of the FARC making a transition to a civilian political force, Santos said his government would agree to them trading bullets for ballots as long as they were not “politicking with their firearms.”

“If the FARC indeed wants to end the conflict and move from bullets to the ballot box, take part in politics and seek to achieve goals in democratic processes, they will find the government most willing and cooperative,” he said.

“But if what they are seeking is once again to put their revolution by decree on the table, over there in Cuba, and change the constitution and the country and its public policy, there won’t be any peace there,” he warned.

Talks are to resume on Wednesday, and will continue to focus on land reform, the first point on the agenda, the parties said in a joint statement.