The launch of a United Launch Alliance Delta 4-Heavy rocket from Cape Canaveral was aborted three seconds before a planned liftoff at 3:28 a.m. EDT (0728 GMT). The rocket was set to loft a classified payload for the National Reconnaissance Office, the U.S. government’s spy satellite agency.

A United Launch Alliance Atlas 5 rocket departs Vandenberg Air Force Base today at 10:30 a.m. local time (1:30 p.m. EST; 1830 GMT) to deliver the commercial WorldView 4 Earth-imaging satellite into polar orbit for DigitalGlobe.

United Launch Alliance called off a test-firing of the company’s first flight-rated Vulcan Centaur rocket at Cape Canaveral Thursday to troubleshoot a problem with the booster’s engine ignition system.