A car bomb at a Colombian military base in June, which injured 44 soldiers including two US military advisers, was claimed by dissident members of a militant group on Wednesday.
Most of the Revolutionary Armed Forces of Colombia, better known as Farc, laid down their arms after a historic 2016 peace agreement.
But a small number of militants, infamous for their role in the country’s illegal cocaine trade, have vowed to continue fighting.
Admitting to the bombing, as well as an attempt to shoot down a helicopter carrying Colombian President Ivan Duque, also in June, was announced by militant commander Javier Alonso Velosa.
Mr Velosa commands some of the estimated 2,500 Farc militants still fighting the government.
He was interviewed by local media in Catatumbo on Wednesday, where he said that the attack targeted "the North American advisers and the leaders of the brigade", the latter a reference to Colombian military commanders.
Farc was formed in 1964 as an anti-government Marxist-Leninist movement in Colombia’s jungle-covered and impoverished hinterlands, after a surge in inequality and poverty in rural areas, which led to a rise in support for Communism, and a series of harsh government crackdowns.
Since the 1970s, the group went from strength to strength, eventually taking over an area of Colombia the size of Switzerland and conducting regular attacks on urban centres.
But an internationally backed peace process, conducted in tandem with wide-ranging economic reforms and international aid, gradually convinced the militants to give up their armed struggle.
The Colombian government also pledged to rein in right-wing militias who were also involved in the drug trade.
The Farc’s former members have also formed a legal political party called Comunes and are participating in transitional justice proceedings, where they have repeatedly asked forgiveness for murders, kidnappings and other crimes.
The government, meanwhile, continues to clamp down on remaining Farc members.
Ten people were arrested in July in Norte de Santander province for involvement in the attacks. The attorney general said at the time that the suspects all rejected the 2016 peace deal and belonged to the dissident 33rd Front.