Russia is scraping across the country to find manpower and weapons, including old tanks based in the Far East, having used up much of its military capacity in the first 100 days of its invasion of Ukraine, according to senior European officials with knowledge of the situation on the ground.

As a result, Russia may be only a few months from needing to slow operations for a major regroup, these people said, speaking on condition of anonymity to discuss matters that aren’t public. The Kremlin might also be forced to announce a mass mobilization in order to call up soldiers to continue the fight, the people said, though that’s something Russian President Vladimir Putin so far has been reluctant to do as it would amount to a public admission the war isn’t going as planned.

Russia’s troubles may not come soon enough to provide relief to Ukraine’s beleaguered forces in the eastern Donbas area. Massively outgunned by Moscow, Kyiv’s forces are losing 100 or more a day, Ukrainian officials say, and have had to slowly give up ground around the cities of Sievierodonetsk and Lysychansk. If Russia takes those two — particularly the more strategic city of Lysychansk still under greater Ukrainian control — it would effectively seize the entire Luhansk region, achieving one of the goals Putin set out at the start of the war.