The decisions by Germany and the United States to send battle tanks to Ukraine, reversing months of resistance, on Wednesday prompted additional pledges from across Europe and predictions of victory over Russia. But it may be months before the tanks rumble across the battlefield.

"These can help Ukraine to defend itself, win and prevail as an independent nation,” said Jens Stoltenberg, NATO’s secretary-general. "Soon to be a regular sight prowling the fields of Ukraine,” Britain’s Defense Ministry crowed in a Twitter post with a photo of a German Leopard 2 tank and a British-made Challenger 2 tank chewing up a muddy training field in Poland.

But not that soon. Ukrainian troops still need to be trained to use the powerful Western war machines, and moving them into the conflict zone is far from an easy task. The tanks that were promised by Berlin and Washington will not be delivered until spring or summer at the earliest — not in time to help Ukraine defend hotly contested towns and cities near Bakhmut, in the country’s east, where Russian forces have been recently advancing in a grueling ground assault.