A former Commander of US Army Forces in Europe has said Ukraine has the chance "to smash Russian forces as they're backpedaling".
Retired Lieutenant General Ben Hodges said the conflict had reached "the decisive phase" and Russia had "obviously" shifted focus to the Donbas region in order to "deliver some sort of victory before 9 May after all their failures over the last six plus weeks".
"We have a chance, actually, for Ukraine to smash Russian forces as they're backpedaling, as they're trying to reconstitute - they're vulnerable," he said.
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It comes after Ukrainian President Volodomir Zalensky warned tens of thousands of Russian troops are being readied for a new offensive.
He was speaking as new satellite imagery shows an eight-mile Russian convoy on its way to eastern Ukraine,
Ukrainian resistance has seen Russia fall back from other areas to concentrate on the region, which includes Luhansk and Donetsk where a rebellion has been fought since 2014.
Ukraine has the bulk of its military forces in the east, and key battles with reshaped Russian forces are expected in the coming days.