Russia’s military is under pressure after a series of bruising battles left its forces exhausted, and it may not have adequate time to re-equip and refurbish them for its push in the Donbas region of eastern Ukraine, analysts say.

In particular, a lack of reserve manpower is forcing Russian commanders to consolidate depleted battalion tactical groups, according to the Institute for the Study of War.

The Institute quoted an anonymous US defence official as saying that Russian forces have had to disband and combine some of their battalion tactical groups in Ukraine to compensate for casualties and other losses.

At the same time, the Institute said that some Russian troops who were withdrawn from around Ukraine’s second-largest city, Kharkiv, in the northeast of the country, have been redeployed toward the Donetsk region in Donbas.

And units that fought in the southern port city of Mariupol can now be sent elsewhere after the surrender of Ukrainian fighters defending a large steel plant effectively subdued the city.

Those forces need to be re-equipped and refurbished before they can be redeployed but Russian commanders are under pressure to demonstrate tangible success, according to a British intelligence report.

“Russia will probably redistribute these forces without adequate preparation, which risks further attrition,” the report, from Britain’s defence intelligence agency, said.

Refurbishing units after combat and giving them a break before they are redeployed is necessary in wars, said Ben Barry, an expert at the International Institute for Strategic Studies.

Riverside city bombed

Russian troops bombarded a riverside city on Friday in what appeared to herald a major assault to seize the last remaining Ukrainian-held territory in a province it claims on behalf of separatists.