In Ukraine’s fight against Russian aggression, neither time nor manpower is on Kyiv’s side. Not only does Vladimir Putin plan to launch a new offensive in the spring; he may do so with additional aid from Chinese strongman Xi Jinping. Recent reports indicate that Mr. Xi will soon visit Mr. Putin for a summit—and that, for the first time, military support may be on the table. Such replenishment of Russia’s depleted weapons inventory could extend the current deadlock into a more dangerous and indeterminable conflict.

Yet the West has something in its arsenal that could fundamentally change the war: combat air power. Several Western nations have recently supplied Kyiv with modern tanks, including the U.S.’s M1 Abrams and Germany’s Leopard, which is a positive development and a diplomatic victory for Ukraine. But tanks have limitations. The gun on a modern tank has a maximum reach of about 3 miles, and the vehicle’s top speed is just above 40 miles an hour. Tanks can’t operate long without tremendous logistical support, both in fuel and maintenance, and won’t do much to change the picture on the ground as the war devolves into an ugly World War I-type stalemate.