Poor discipline could be to blame for Russian troops using mobile phones on the battlefield, according to a defence expert in the analysis of a deadly strike by a Ukrainian missile that killed at least 89 of Putin's troops.
The comments about the incident that led to the deaths of Russian recruits during the ongoing conflict in Ukraine have been made by Shashank Joshi, defence editor at The Economist.
Also a visiting fellow at the Department of War Studies at King's College London, Mr Joshi cited a lack of discipline, coupled with advances in technology, as being the cause of a group of Russian soldiers being tracked by their mobile phones, and then killed in a rocket strike by Ukrainian troops.
The Ukrainian missile strike hit a temporary Russian barracks in a vocational college in Makiivka, in the occupied Donetsk area, on 1 January, resulting in the deaths of at least 89 soldiers.
Russian General Lieutenant Sergei Sevryukov said that phone signals allowed Kyiv's forces to locate the co-ordinates of the recruits and launch a strike in the region.
It was one of the deadliest strikes on the Russian army during the 10-month-long conflict, Russia says.
Mr Joshi said: "(It's) entirely plausible that mobile phones were the way in which Ukraine identified this concentration of forces.
"We know that they've had problems with their encrypted radios at times and, therefore, they have resorted to more natural ways of communicating.
"We also know that their discipline in terms of carrying mobile phones, taking imagery, making phone calls, has been poor at times."
The Russians have stated they intend to put measures in place to prevent the attack on their forces from being repeated.
Mr Joshi continued: "Hundreds of thousands of young men mobilised as conscripts to the frontline, some of whom died in the blast, would be more vulnerable to detection.
"Ukraine can detect military radios because that's what military electronic warfare equipment does, so mobile phones are not the only way to make yourself vulnerable.
"But they are a useful way to spot troops because they're not designed to be secure – they send signals in a variety of directions."
Intelligence underpinning a strike like the one on 1 January often features layers of signals, not just from mobile devices.
The 'tip and cue' monitoring technique used between complementary platforms in battle was suggested by Mr Joshi as a possible method used to obtain the coordinates of the facility.
"You may spot a clue with one sensor – for example, your electronic antennae. That may allow Ukrainians to then call upon satellite imagery to get a detailed look at the facility, to look at the vehicles around it, the movements around it, perhaps they can task a drone to fly near it.
"It may be that mobile phones give away your location, but other sensors are subsequently used to confirm the details or to triangulate the exact location in ways that allow military targeting on a precision basis."