Later, during a signing ceremony for an environmental education pact, the president said the announcement by the Revolutionary Armed Forces of Colombia, or FARC, guerrilla group was a positive development but still not “sufficient.”

“What we want in this country is to end this conflict as soon as possible,” Santos said.

To that end, the president called for accelerating the negotiations – particularly on the thorny issue of transitional justice – and reiterated that only once a final agreement has been reached will the FARC secure the bilateral truce they are seeking.

The FARC said Wednesday in Havana it was declaring a one-month cease-fire in Colombia effective on July 20.

The rebel insurgency made the move in response to calls from Cuba and Norway, the two guarantor countries for the peace process with the Colombian government in Havana, as well as Venezuela and Chile, for a reduction in the intensity of the conflict, said the guerrilla group’s second-in-command, Ivan Marquez.

“We are announcing our willingness to order a unilateral cease-fire as of July 20 for one month. We are seeking to create favorable conditions to move forward with the other party in reaching a bilateral and final cease-fire,” the FARC said in a statement.

The Colombian government and the FARC have been holding peace talks in Havana since November 2012 aimed at bringing an end to a more than 50-year-old armed conflict.

The FARC had previously announced a unilateral cease-fire last December, and three months later the Colombian government ordered a halt to the bombardment of guerrilla encampments.

But the intensity of the conflict ratcheted up again after 10 enlisted men and a non-commissioned officer died in a FARC attack on an army detachment in early April.

Santos responded by announcing the resumption of the bombing raids, and the FARC in May suspended their months-old unilateral cease-fire after 26 insurgents were killed in an army bombardment of a guerrilla encampment in the southwestern province of Cauca.

The FARC, Colombia’s oldest and largest leftist guerrilla group, was founded in 1964 and operates across a large swath of the Andean nation.