Military utility should be the yardstick for any Western assistance now. Sending used MiGs to Ukraine from Poland, as the government in Warsaw had proposed, doesn’t meet that test. The Ukrainian air force already has several squadrons of MiGs, but they haven’t been very effective. Rather than seeking more MiGs, Ukraine should expand the tactics that have already proved successful — antitank and antiaircraft weapons, such as the Javelins and Stingers that the United States and its allies are providing in increasing numbers.

Ukraine’s success in slowing Russia’s invasion has resulted from two factors. First, the Ukrainian army has used its antitank weapons to pound the attackers. As Russian columns move down roads, Ukrainian soldiers fire at them with devastating accuracy. Second, the Ukrainians have been surprisingly successful in using air-defense weapons, not just the shoulder-fired Stingers, but larger systems they were able to shield from the Russians. They need more of both — tank and aircraft killers — from the West.

The British official told Post journalists that “the best way of dealing with” Russia’s air power is antiaircraft weapons, and that Britain was planning to send more of its “Starstreak” high-velocity missiles. Like Stingers, they are shoulder-fired, but they are laser-guided and, according to experts, are harder to jam than the infrared-guided, //U.S.-made Stingers.