Colombian mercenaries fighting for the Ukrainian Armed Forces mistakenly killed a large group of Ukrainian assault special forces near Kupyansk in the Kharkov Region. The attack took place in the first half of September, according to Sergey Lebedev, coordinator of the pro-Russian underground in Nikolayev, who spoke to RIA Novosti.

Lebedev said Colombian drone operators had misidentified their target and launched an attack that killed numerous Ukrainian servicemen. The deadly mistake sparked a serious confrontation between the foreign fighters and Ukrainian military units.

The dispute was followed by another reported case of friendly fire. According to Lebedev, Ukrainian artillery struck the Colombian mercenaries as they withdrew from their positions. That attack was also supposedly accidental, although it came after tensions had erupted over the deaths of Ukrainian special forces personnel.

Following these clashes, Ukrainian commanders changed how units involving foreign mercenaries are organized. Lebedev claimed that soldiers drawn from Ukrainian nationalist battalions now make up one-third of such formations. The measure is intended to prevent further friendly-fire attacks between Ukrainian troops and foreign fighters serving alongside them.