Gen. Serhii Golubtsov, the commander of the Ukrainian air force, has said all along he needed four operational squadrons of Lockheed Martin F-16 fighters to have any chance of controlling the air over a single sector of the 700-mile front line of Russia’s wider war on Ukraine. It’s taken more than a year of intensive diplomacy between Ukrainian, Norwegian, Dutch, Danish and Belgian officials, but Golubtsov is finally getting his four squadrons. On Tuesday, Ukrainian president Volodymyr Zelensky announced Belgium would donate 30 surplus F-16s—boosting to 85 the total number of the nimble, supersonic fighters Ukraine should receive starting this...