For now, “our task is to keep guns and ammo flowing,” says one senior defense official, who described the rush to provide weapons. “If we do that, the Ukrainians will stay in the fight. … They will not put their arms up in defeat.”

As Round 2 begins, Russia appears to be attempting a classic pincer movement to crush Ukrainian forces in the east. The Russian assault will push west from the Donbas region, but also south from the Kharkiv area and north from the coast near Mariupol. The aim is to annihilate Ukraine’s army in this eastern pocket, U.S. analysts believe.

The Russians have every advantage in this fight but one: It’s not their land. Ukrainians have shown that they can mount a courageous and disciplined defense against a numerically stronger Russian force, as they did in repelling Russian attacks against the capital of Kyiv last month.