The Ukrainian military is firing thousands of artillery shells a day as it tries to hold the eastern city of Bakhmut, a pace that American and European officials say is unsustainable and could jeopardize a planned springtime campaign that they hope will prove decisive.

The bombardment has been so intense that the Pentagon raised concerns with Kyiv recently after several days of nonstop artillery firing, two U.S. officials said, highlighting the tension between Ukraine’s decision to defend Bakhmut at all costs and its hopes for retaking territory in the spring. One of those officials said the Americans warned Ukraine against wasting ammunition at a key time.

[DS–war is always about trade-offs. Is Ukraine right to fight this battle?]