KYIV: Russia has acknowledged its worst-ever military losses from a single Ukrainian attack with the death of at least 89 servicemen in Makiivka in eastern Ukraine over New Year.

Here is what we know about the strike:

What happened in Makiivka?

Russia’s defence ministry on Monday said in an extremely rare announcement that 63 Russian soldiers were killed in a strike carried out using Himars rocket systems supplied by the United States to Ukraine.

On Wednesday, the ministry said the toll had risen to 89 after more bodies were discovered.

The strike took place in Makiivka, a small city in the Donetsk region, a part of Ukraine that has been under the control of pro-Russian separatists since the beginning of the conflict in eastern Ukraine in 2014.

Senior Russian military official Lieutenant General Sergei Sevryukov said Ukraine had hit a temporary base in Makiivka at 12:01 am local time on January 1, using US-supplied HIMARS rocket systems

It was the biggest-ever loss of life in a single attack acknowledged by Moscow since it began its invasion in February.

The incident was also the first communication about any military deaths since September, when Defence Minister Sergei Shoigu gave a toll of 5,937 soldiers killed to that point.

What do the Ukrainians say?

Ukraine on Monday took responsibility for the strike and said it occurred on December 31 during a wave of Russian strikes on Ukrainian targets.

The Ukrainian army’s strategic communications department said that nearly 400 soldiers were killed and 300 injured in the strike in Makiivka.

But the general staff of Ukraine’s armed forces said it did not have a final toll and announced only that “up to 10 units of enemy military equipment” had been destroyed.

Why so many deaths?

Russia’s military leadership blamed the high number of casualties on the use of cell phones by their soldiers.

Sevryukov said the army had determined that the reason for the high death toll “was the turning on and massive use by personnel of mobile phones within reach of enemy weapons”.

Ukrainian forces simply said there was a “concentration” of soldiers in Makiivka.

Russian drones attack critical infrastructure in and around Kyiv

Russian and Ukrainian sources began reporting on the strike on Sunday, saying that Russian mobilised personnel – not professional soldiers – had been killed.

Former separatist commander Igor Strelkov, who is familiar with the situation on the ground, said the building was “almost completely” destroyed because ammunition stored on the premises detonated in the strike.

He said “hundreds” had been killed and wounded.

What has been the reaction in Russia?

The announcement of the losses caused shock in Russia as well as criticism of Russia’s high command, which has already been humiliated by a series of battlefield reversals in recent months.

“Despite several months of war, some conclusions have still not been drawn,” wrote blogger Boris Rozhin, who is close to the separatists, criticising the “incompetence” of Russian military leadership.

Alexander Kots, a war correspondent, wrote: “Why do we keep putting up (the mobilised personnel) in hotels, hostels and professional schools?”.

Strelkov said another deadly strike could happen “at any moment”, adding that Russian generals were “incapable of learning”.

The US-based Institute for the Study of War predicted Russia’s defence ministry would try to “deflect the blame for its poor operational security” onto local officials and mobilised personnel.

In a rare public commemoration, some 200 people gathered in the Russian city of Samara – where some of the victims came from – to commemorate the dead.

Mourners laid flowers at a city monument, an Orthodox priest recited a prayer for the dead, and soldiers fired a gun salute.