Ukraine’s forces have lost a large share of their most experienced soldiers, having suffered an estimated 120,000 casualties. Purportedly leaked US intelligence documents have suggested that the counteroffensive could fall “well short” of Kyiv’s goals.

Yet Ukraine’s army has been underestimated before, such as when it defied western military assessments last year and pushed back Russian forces from around the capital and then the northeastern city of Kharkiv. Russia has also lost almost twice as many men since the full-scale invasion, according to western assessments. Moreover, Ukrainian troops are better equipped and trained than their foes.

“If the Ukrainian attack is hard and fast and gets behind the Russians, the frontline will unravel and the Russians will run . . . just as they did during the counter-offensive around Kharkiv,” said Glen Grant, a former British army officer and adviser to the Ukrainian parliament’s defence committee.