There was a time not so long ago when the young Ukrainian drone operator could take out Russian tanks and armoured vehicles almost at will.

Just over six months ago, Darwin – to use the radio call sign by which he prefers to be known – racked up a personal record by  single-handedly destroying or damaging nine of the combat vehicles in one day.

This is no longer the case. 

In recent months, the Russians have become more adept at electronically jamming the first-person view (FPV) drones that Darwin’s battalion once operated with such devastating effects along the Kupiansk front line in northeastern Ukraine.

It is, Darwin reckons, one of the main reasons – greater perhaps than Russia’s manpower advantage – that Ukraine is on the back foot not just around the embattled town of Kupiansk but along much of the 700-mile front line.

As a result, Kupiansk, which was once a potent symbol of Kyiv’s ability to triumph against the odds, has become emblematic of a starker reality that the Trump administration will point to as justification for ceasefire talks and a rapid end to the war.