For weeks, Ukrainian forces have been probing Russian defences in the southeast, looking for an opening to push their armoured vehicles behind the main Russian line. But artillery fire and Russian counterattacks had been too intense to allow Ukrainian armour to pass.

This week, though, Ukrainian armoured vehicles advanced past Russia’s main anti-tank defences at one location on the front line, according to reconnaissance video and commanders, showing slight progress in Kyiv’s halting counteroffensive.

Lieutenant Ashot Arutiunian, the commander of a drone reconnaissance unit operating in the area, said the vehicles had broken through near Verbove, a village in the Zaporizhzhia region. The vehicles, however, are confined to slender routes through minefields and have little room to manoeuvre, he said.

Earlier, Ukrainian tanks had broken through a less formidable layer of defences, and infantry had pierced a second line, seen as Russia’s main anti-tank barrier.

The breach, a swathe of farm fields and tree thickets 1 mile or so wide, is a crucible of concentrated Russian and Ukrainian artillery fire, littered with blown-up vehicles and dotted with craters. It sits near Robotyne, a village that Ukrainian forces captured several weeks ago.

The recent breakthrough, shown in unverified videos published on Thursday, suggested that weeks of bloody infantry fighting had secured the breach sufficiently to move heavy weaponry forward. That would be a positive step for Ukraine in its campaign to drive Russian forces from the south. More Russian minefields and anti-tank barriers remain ahead.

The breach of defences in the Zaporizhzhia region was first reported by The Wall Street Journal. It is unclear whether the Ukrainian vehicles that breached the defences can gain control of their new positions securely enough to be based behind Russian lines.

New York Times News Service