The launch of a Delta IV Heavy rocket from Cape Canaveral has been pushed back five days.

United Launch Alliance had scheduled the launch, named NROL-37, for Saturday, June 4. The Delta IV Heavy, one of the nation's most powerful rockets, was set to carry a classified payload for the U.S. National Reconnaissance Office into orbit.

The launch is now set for Thursday, June 9. The launch window runs from 1:30 p.m. to 6:35 p.m.

According to ULA, the delay came at the request of the U.S. National Reconnaissance Office.

The NROL-37 spacecraft and launch vehicle are secure on Space Launch Complex 37, officials said in a statement.