BRUSSELS—NATO will plow funds into stationing U.S. military equipment in Poland, lending allied heft to Washington’s strategy for quickly reinforcing Europe with troops in case of a Russian incursion.

The $260 million storage facility will help turn an air base near Powidz, in central Poland, into a hub for U.S. forces in a former Soviet Bloc country that has a land border with Russia. Construction will start this summer and take two years, said Jens Stoltenberg, secretary-general of the North Atlantic Treaty Organization,...