Ukraine’s counteroffensive, soon to enter its fourth month, is at best making marginal gains along the 1,000-mile front line. Russia’s network of defenses, composed of minefields, machine-gun nests, anti-tank traps, and trenches, has proven to be a formidable obstacle for Ukrainian troops tasked with pushing the hundreds of thousands of Russian troops further east. U.S. Joint Chiefs of Staff Chairman Mark Milley’s assessment back in July has turned out to be prescient: “It’s going to be very long, and it’s going to be very, very bloody.”