ARTYOMOVSK, Ukraine – A car slows to a halt and its lights blink off as a flickering torch approaches through the dark, fog-choked night. Behind the torch, a helmeted figure appears, the Kalashnikov strapped across his chest intermittently illuminated by the soft orange glow of hazard warning lights.

The tension is palpable at

this concrete-clad blockpost on the road east to Donetsk, where Ukrainian and

Russian artillery have been hammering each other with massed fire for the past

three days in an effort to establish control over the devastated ruins of the Donetsk airport.