May 9 is the date Russia marks the Soviet victory in World War Two with an annual military parade overseen by Russian President Vladimir Putin on Red Square.

Moscow's rapid capture of the town with a pre-war population of 12,200 to the west of the occupied city of Bakhmut would indicate growing Russian battlefield momentum as Ukraine grapples with a slowdown in Western military aid.

Colonel General Oleksandr Syrskiy, who warned this weekend that the situation in the east had deteriorated, said Russia was focusing its efforts west of Bakhmut to try to capture Chasiv Yar before moving towards the city of Kramatorsk.

Kyiv's brigades were holding back the assaults in the Donetsk region for now and had been reinforced with ammunition, drones and electronic warfare devices, he said in a statement on the Telegram messenger.

"The threat remains relevant, taking into account the fact that the higher Russian military leadership has set its troops the task of capturing Chasiv Yar by May 9," he said, without elaborating.

The war has escalated in recent weeks with Russia staging three massive air strikes on Ukrainian power plants and substations, raising fears over the resilience of an energy system that was hobbled in the war's first winter.

BIG OFFENSIVE

More than two years since Russia's full-scale invasion, President Volodymyr Zelenskiy has warned the Kremlin may be preparing to launch a big offensive in late spring or summer.

It is unclear where that attack would come, but Russia has focused its attacking efforts in the eastern Donetsk region.

Ukraine has this year tried to find a pressure point to strike back against the Kremlin, using domestically-produced long-range drones to bomb oil facilities deep inside Russia.

Chasiv Yar, which is bisected by a canal, lies 5-10 kilometres (3-6 miles) from Bakhmut, the devastated city captured by Russia in May last year after months of bloody fighting.

Ukraine now faces manpower challenges and artillery shell shortages, aggravated by a long delay in vital U.S. military assistance that has been stalled in Congress for months.

Rob Lee, a senior fellow at the Foreign Policy Research Institute, a think-tank in Philadelphia, said on X that Chasiv Yar would likely prove an important battle.

"Chasiv Yar is located on defensible high ground. If Russia takes the (town), they could potentially increase the rate of advance deeper into Donetsk (region) as part of an expected summer offensive," he said.

"Russian forces will still have to cross the canal to take the (town), but they have now reached the canal southeast of the (town). Immediate increased deliveries of ammunition could prove critical."

(Reporting by Tom Balmforth; Editing by David Holmes)

By Tom Balmforth