It’s reckless, if not insane, to deploy an open-top, unarmored all-terrain vehicle—in essence, a heavy-duty golf cart—in combat just a quarter mile from the front line. But two years into Russia’s wider war on Ukraine, Russian commanders are at least reckless if not not insane. Apparently this weekend, a Russian unit—possibly the 488th Motor Rifle Regiment—attacked positions held by the Ukrainian 60th Mechanized Brigade in Yampolivka, in eastern Ukraine’s Donetsk Oblast. A Russian column including what appeared to be MT-LB armored tractors and at least one T-90 tank motored west toward Yampolivka. That itself wasn’t unusual. What was unusual was...