By most accounts, the war in Ukraine is the largest war on the European continent since the end of World War II. But just how calamitous the conflict has been in human terms, those killed and wounded, remains unknown.

The United States military now estimates that 180,000 Russian soldiers and more than 100,000 Ukrainian troops have been killed or wounded in the invasion of Ukraine. Officials say there is a sizable margin of error attached to the striking figures, though they did not elaborate on just …