A top secret U.S. government satellite launched atop a Delta IV rocket this morning.

It’s a spy satellite designed to gather intelligence for the United States government. The rocket took off from Vandenberg Air Force Base in central California. United Launch Alliance prepared the rocket for liftoff.

ULA has been busy. This past Friday, the company launched an Atlas V rocket from Florida’s Space Coast with a GPS satellite on board.

Wednesday’s satellite, called NROL-45, was encapsulated and mated on top of the Delta IV.

The satellite is for the National Reconnaissance Office, which was formed in response to the Soviet launch of Sputnik to oversee both overt and covert spy satellites and projects.

The rocket took off at 6:40 a.m. Eastern. The mission is so classified that ULA did not disclose how long the launch window would last.

Elsewhere, NASA announced that the next Atlas V launch from Cape Canaveral Air Force Station would be pushed back more than a week to accommodate more cargo processing for transport to the International Space Station. The launch of the OA-6 mission, which will carry a Cygnus spacecraft to the ISS and was previously announced for March 10, will be no earlier than March 20.