Colombian President Juan Manuel Santos and the head of the Revolutionary Armed Forces of Colombia (FARC), Timoleón Jiménez (aka Timochenko) have announced a definitive bilateral ceasefire to end over 50 years of conflict.

Speaking from Havana, Cuba on 23 June, the FARC guerrilla and Santos’ government sealed progress made during the past few months during the peace talks, which began in November 2012.

It marks a point of no-return. Both parties have reached a stage in which resorting to violence is no longer an option, as a bilateral ceasefire binds them both to a definitive truce. This builds on a unilateral ceasefire by the guerrilla in December 2014, and marks the culmination of a bilateral de-escalation process, which was formally entered last year. These previous truces had already successfully stopped hostilities better than any other attempts to end the conflict, which has claimed the lives of over 250,000 people.

Why has this deal succeeded where other attempts failed? One of the main reasons is that it guarantees the rights and safety of the demobilized FARC rebels, one of the most controversial items in the negotiations’ six-point agenda.

The FARC had good reason to be wary. An earlier peace process in the 1980s between the FARC and Belisario Betancur’s administration (1982-1986) led to the creation of the Unión Patriótica (UP), a political party composed largely of former FARC members and other leftist activists. Soon after its foundation, paramilitary groups and the army targeted the UP, killing thousands. By 2000, virtually all of the UP’s members had either been assassinated or forced to abandon the party.

What Thursday announcement makes clear is that things have changed dramatically: not only do the State and the military no longer embrace the anti-leftist discourse of the kind waged against the UP in the 1980s, they have now formally agreed to help the guerrilla in their de-mobilization process and their future entry into political life.

Under the detailed agreement, members of the FARC will settle temporarily in specific zones. The guerrilla will be given six months to surrender its weapons, while all Colombians are being called upon to vote on the final agreement via a public referendum.

This last detail shows that the FARC, like the state, have undergone significant changes. The FARC had always opposed the idea of a referendum but has finally aligned themselves with the government’s position. Thursday’s agreement made clear that the mechanism that will be used to ratify the treaty will be decided by Colombia’s Constitutional Court. This is yet another major breakthrough for the negotiations and for the very prospects of Colombia’s peace because by accepting the decision of the Constitutional Court, the FARC are effectively agreeing to play by the rules, recognize the legitimacy of a State they had historically opposed, and the legal process by which the final treaty will come into force.

Another factor that makes this deal likely to stick, is that the government has promised to address some of the social deficits and gaping inequality in Colombia that prompted the formation of the FARC 52 years ago, with a programme to invest and develop rural areas with high levels of poverty.

The agreement announced by Santos and Timochenko this Thursday may not bring about, by itself, an end of Colombia’s armed conflict. Another guerrilla force, the Ejército de Liberación Nacional (ELN) has only just embarked on a separate peace process with the government and there are still a number of key points in the six-item agenda of negotiations with the FARC that must be addressed before the treaty can be signed – Santos hopes this will happen in July.

Santos’ closing words in Havana were telling. Addressing Timochenko, he made it clear that while he will never share the commander’s political or economic views, the day has finally come in which both are able to dissent peacefully.

This heralds a new phase in Colombia’s history. In a country that has got used to living in a state of perpetual warfare, the handshake between Santos and Timochenko shows all the signs of being a prelude to a much-needed and longed-for peace.