Commander Roman Ruiz of the Revolutionary Armed Forces of Colombia (FARC) was killed after Colombian government forces bombed the guerrilla group in northwest Colombia. The FARC leader perished alongside four other rebels in the Choco region, just hours after peace talks resumed in Cuba on Monday, teleSUR in Venezuela reported.

Colombian President Juan Manuel Santos resumed military operations against the guerillas last month, after the FARC broke a unilateral ceasefire and attacked government forces in the Cauca region of southwest Colombia. “This is the wrong path, and it is obvious peace will never be reached by escalating the conflict,” FARC negotiator Pablo Catatumbo said during the peace talks in Havana Monday, according to teleSUR. “The Colombian people demand peace. Santos was re-elected for a second mandate so he could achieve peace. Our peace delegation was sent by all the guerrillas in the country for the same objective.”

Catatumbo said government airstrikes, which killed 26 rebels earlier this month, were a “setback” for peace talks. The massacre was the deadliest since the FARC and the Colombian government began negotiations two years ago. The deadly raid prompted the FARC to suspend its unilateral ceasefire on Friday, teleSUR reported.

“Gentlemen of the FARC: it is time to speed up negotiations. How many more deaths do we need to understand it’s time for peace!” Santos said on Twitter on Friday.

The suspended ceasefire and resumed airstrikes have jeopardized the peace process between the Colombian government and the FARC rebels. The five-decade conflict has killed more than 220,000 people and displaced more than 5 million. The warring sides have been in negotiations to end the conflict since 2012.

The FARC was established in the 1960s as the military wing of the Colombian Communist Party following an attack on rural Communist territories by the right-wing Colombian army. What began as a peasant movement has grown into a leftist guerrilla organization that has since sustained violent conflict with successive Colombian governments, according to Reuters.