WASHINGTON—The U.S. is providing spy-satellite imagery to Ukraine to help in its fight against Russia-backed rebels, but with a catch: the images are significantly degraded to avoid provoking Russia or compromising U.S. secrets.

The White House agreed last year to Ukraine’s request to provide the photos and other intelligence. But before delivering them, U.S. officials black out military staging areas on Russian territory and reduce the resolution so that enemy formations can’t be clearly made out, making them less useful...