Monday morning's scheduled launch of a rocket carrying satellites for the US Air Force and NASA was called off, NASA spokesman Keith Koehler said.
No other details were immediately available.
The launch from the Virginia shore would have been the first takeoff from the mid-Atlantic region's commercial spaceport.
The rocket will transport the Air Force's TacSat-2 satellite to test the military's ability to transmit images of enemy targets to battlefield commanders in minutes - a process that now can take hours or days. The Air Force envisions a system that would allow commanders to send questions directly to a satellite overhead and receive answers before the satellite passes back over the horizon.