When Russia invaded Ukraine in February 2022, it did so as a far larger, richer and more powerful nation than its victim, with greater resources of manpower, industrial capacity and raw materials than the Kyiv government could ever hope to wield. For all the shifting tides of the war so far, this essential imbalance has not changed. Now it’s finally bearing fruit for Moscow. Ukraine’s Kursk incursion has been characterised as a strategic misstep, denuding the defensive...