Ukraine was biding its time: while outside analysts downplayed their chances, the Ukrainians were quietly planning an offensive across the Russian border

Earlier this week, reports began filtering in that Ukrainian forces had entered Russia’s Kursk province, in what many analysts assumed was a small cross-border raid—of a sort that Ukraine has attempted a few times since Russia’s full-scale invasion in 2022. But as the hours and days ticked by and Ukrainian forces moved...