More than 100 Russian soldiers were reportedly killed when a volley of Atacms missiles hit a training base in eastern Ukraine in one of the highest single losses of Russian lives in months.

Drone footage shared on social media appeared to show at least four of the short-range ballistic missiles, armed with cluster warheads, smash the gathering of Russian troops in as little as 95 seconds.

Ukraine has been begging the US for months to supply high-precision, long-range Atacms missiles, before they were secretly shipped to Kyiv last month.

Western analysts said the attack occurred on a Russian training centre between the towns of Kuban and Mozhnyakivka, about 50 miles behind the front lines in the Donbas region of Luhansk.

The strikes reportedly killed 116 Russian troops, the US-based Institute for the Study of War think-tank wrote in a report on Wednesday.

‘Such strikes are crucial’ 

Neither the Russian nor Ukrainian defence ministries have commented on the reported attacks. But surveillance footage from a Ukrainian drone showed a grouping of Russian forces and at least three armoured vehicles.

At first, a dud missile appeared to smash into a field in the vicinity of the troops, sending a plume of dark smoke into the air. Shortly after comes a rapid burst of three explosions that blanket the area, with the distinctive smoke trails from cluster bomblets being scattered and detonated.

The Russian troops were preparing for an offensive on the neighbouring Kharkiv region, Oleksandr Musiienko, head of Ukraine’s Centre for Military-Legal Studies, said.

“Such strikes in the Luhansk region are crucial,” he said. “It’s precisely in the territory of the northeastern part of the Luhansk region that Russia has been training and coordinating its units, which were specifically preparing for an escalation of hostilities in the Kharkiv region, where Russia plans to reinforce its advance.”