Heavy shelling and fierce street battles are helping Ukrainian forces gain the upper hand over pro-Russian separatists in and around the eastern rebel strongholds of Donetsk and Luhansk.
The Kremlin denies orchestrating the rebellion. But near Luhansk, Kyiv claims to have seized two armoured vehicles belonging to a Russian airborne division, presented as proof of Moscow’s involvement.
“In one of the cars, a complete package of documents was found – a driver’s licence and military documents,” said Ukrainian National Security Council spokesman Andriy Lysenko.
His claims have been dismissed by Russia’s Defence Ministry.
Tightening the noose around the main rebel bastions comes at a cost. The UN says more than 2,000 people – combatants and civilians – have died in this conflict.
Some are caught in the crossfire trying to flee the frontline.
Ukraine said on Thursday that three refugees including a five-year-old child were killed when rebel gunfire hit their car near Luhansk.
The deaths follow those of around 17 refugees killed when rocket fire hit a convoy of buses leaving Luhansk on Monday. Both sides blamed each other for the attack.
People are fleeing fighting but also increasingly desperate living conditions.
Luhansk has been largely cut off for weeks and is in its 19th day without water and regular supplies of electricity.