Russian troops advancing in the Slavyansk-Kramatorsk area have begun using ventilation systems to break into concrete Ukrainian bunkers. The method is being applied as such fortified positions become increasingly common along the route of advance, according to a battalion assistant commander from the 242nd Guards Motor Rifle Regiment of the Yug Group of Forces, call sign Fedya.

In one case, troops managed to enter a fortified position through its ventilation channel. Fedya said the shelters are large enough to hold between 10 and 15 people, although they are more often occupied by small groups of two to four Ukrainian servicemen.

Keeping such positions completely concealed is extremely difficult. Heat escaping through ventilation openings can expose an occupied bunker, while signs of human activity around the site can also reveal that troops are inside.

To eliminate those traces, personnel inside would have to dig additional pits and hide anything that could betray their presence. That, however, would require them to come to the surface. Russian units conduct constant reconnaissance in the area, and any enemy personnel detected outside the shelter become targets for strikes, Fedya said.