Four Colombian soldiers were killed on Monday when their helicopter landed in a minefield, the latest attack attributed to leftist rebels as both sides in the country's long-running conflict harden their positions amid languishing peace talks.
The Black Hawk chopper carrying the soldiers flew to the volatile Catatumbo region to escort workers repairing an oil pipeline damaged by a recent bombing by the Revolutionary Armed Forces of Colombia.
Six more soldiers were injured, the army said in a statement, without providing more details.
The incident, which the military characterized as an "assassination" in violation of international law, was the deadliest in a string of attacks by the FARC since the rebel movement in May lifted a six-month-old cease fire to facilitate the peace talks taking place in Cuba.
The decision to resume fighting came in retaliation for a military air attack on a guerrilla camp that killed 26 rebels, including a former FARC envoy to the peace talks.
In a clear demonstration of the FARC's still substantial firepower, rebels in recent days have carried out a string of attacks on police stations, oil tankers and valuable energy infrastructure, including the bombing of a transmission line that left more than 400,000 people in the port city of Buenaventura without power for days.
While nobody is expecting the peace talks to be broken off anytime soon, hope for an accord is fading amid the slow progress at the negotiating table and looming legislative elections in October that could give strength to hardliners opposed to the talks.
Colombians' support for the peace process has fallen to around 50%, its lowest level since the talks began more than two years ago, according to a Gallup survey in April taken before the latest wave of violence provoked further public anger at the guerrillas.