Colombian peace talks took another blow on Monday when the Revolutionary Armed Forces of Colombia, or FARC, took out a military helicopter with a land mine, killing four soldiers and injuring six, officials said.
The military said it was likely the mine that struck the helicopter was detonated remotely, Reuters reported. The US-made Black Hawk UH60 was carrying ground troops to assist with the repair of an oil pipeline that was hit by rebels last week.
Colombia's army announced on Twitter that it was investigating. By Tuesday morning, the FARC had not taken responsibility for the incident.
The explosion took place in the rural settlement of Teorama, in the region of North of Santander, near the Venezuelan border. North of Santander has long been a hotbed of guerrilla activity, in part due to mining projects based there.
The FARC has ratcheted up attacks against Colombia's oil infrastructure and other economic targets since the guerrilla group suspended its unilateral ceasefire in May, after the military killed 26 rebels in an airstrike.
Violence is escalating on both sides of Colombia's five-decade conflict, with the military on Monday capturing one of the FARC's financial leaders, Huber Velasquez Galindo, alias 'Andres Chorizo,' reports said.
One of the biggest blows to Colombia's infrastructure was dealt earlier this month when the guerrilla group intercepted a caravan of oil trucks on June 8 in Putumayo, forcing the drivers of 19 tankers to spill an estimated 200,000 gallons of crude onto roadways.
Nearby water sources and farming grounds were contaminated as a result.
The FARC launched another offensive on June 16, when rebels attacked the Limon-Coveñas oil pipeline, spilling oil into the Catatumbo river and igniting a fire that destroyed several houses in the area. The helicopter in Monday's fatal incident was carrying troops to safeguard and repair the pipeline.
A day after the Limon-Coveñas pipeline attack, the guerrilla attacked another point in the pipeline in the municipality of Tibu, also in North of Santander. Authorities are still determining the extent of damages caused by the strike. The 16,000 inhabitants of Tibu are now facing a critical water shortage due to the spill.
Colombia's national oil company Ecopetrol has suffered 22 attacks so far this year, leading to a loss of $2.1 billion dollars and untold ecological damages.
The FARC is trying to show "the government that they're not beaten and that they have the power to really impact national life and the economy," Adam Isaacson, a senior associate at the Washington Office on Latin America, told VICE News.
"They're trying to convince the government that they have to negotiate," he added. "It's the quickest way out, because they've not defeated them on the battlefield."
Despite the violence, the FARC again called for a bilateral ceasefire on Tuesday morning.
"Lamenting the news of deaths in combat, which could be avoided with a bilateral ceasefire, we once again call on President Santos to explore the possibility of stopping the war," the rebels said in a communique.
Isaacson told VICE News that a ceasefire should be a "occupying a lot of their time right now."
The shaky peace talks between the government and the FARC continue in Havana amid the bloodshed. The talks hope to bring an end to the hemisphere's longest war, which has killed 220,000 and displaced millions, mostly civilians.
Follow Joe Parkin Daniels on Twitter @joeparkdan.