Colombia's government and the country's second biggest rebel group have started talks to end a five decade-long conflict that has killed hundreds of thousands of people and forced millions from their homes.
The government and the National Liberation Army (ELN) began peace talks on Tuesday in neighbouring Ecuador after more than three years of failed attempts.
The ELN hopes to clinch an agreement similar to that negotiated last year with the Revolutionary Armed Forces of Colombia (FARC), which allows the rebels to form a political party in exchange for laying down their arms.
In November of last year, President Juan Manuel Santos' government managed to seal an agreement with the FARC after an often difficult almost four-year process. Experts, though, have warned that the ELN will be a tougher negotiating partner than the FARC.
The government's chief negotiator, Juan Camilo Restrepo, said at the opening ceremony that "the time of politics with weapons must end in Colombia.
"Every unnecessary delay in the search for peace means the sacrifice of lives and it is time lost to lay the foundations of reconciliation," he added.
On the table are issues including political participation, disarmament and compensation for victims.
"Many obstacles lie ahead, starting with the fact that the presidential elections loom in Columbia," Al Jazeera's Alessandro Rampietti, reporting from Bogota, said. "They’ll be held in 2018, and it's far from certain that the next president will be as steadfast as Santos has been."
He said that during Tuesday’s talks, the ELN seemed to be have a more "conciliatory tone", telling both the Colombians and the international community that "they will not disappoint them".
Formal negotiations were delayed from November 2016 pending the release of a prominent politician the group held hostage for nearly 10 months.
The release last week of former congressman Odin Sanchez removed the final obstacle to the peace process, which is expected to go on for months before showing any tangible results.
Deaths, disappearances, displacement
Restrepo said that if the ELN failed to give up kidnapping it would be "very difficult to advance" the negotiations.
The ELN's chief negotiator, Pablo Beltran, said that "we all have to change," and called on the government to take responsibility for its part in the conflict.
"We are willing to take responsibility for the events that occurred during the conflict, and we expect the other side to do the same," he said in a speech that referred to the government as a "regime".
"Fortunately today in Colombia we are trying to develop a political solution to the conflict."
More than five decades of conflict involving the two rebel movements, the army and right-wing paramilitary groups has resulted in more than 260,000 deaths, the disappearance of tens of thousands, and the displacement of about six million people.
The leftist ELN is considered a "terrorist" group by the United States and the European Union. It has extorted, bombed oil and electricity infrastructure and kidnapped hundreds of people in its 52 years of existence to raise funds for the war and put pressure on the government.
Colombia is the last country to see major armed conflict in the region. Peace with the two rebel groups could allow for economic development in previously rebel-held areas.
Source: Al Jazeera and news agencies