The United Launch Alliance and the US Air Force have launched a top secret satellite for the National Reconnaissance Office using a Delta 4 heavy launch vehicle.

The launch was delayed until Sunday night.

Using Launch Complex 37 at Cape Canaveral, the Delta 4 was lifted off at at 5:58pm EST.

The National Reconnaissance Office operates the US fleet of imaging and radar satellites along with various other satellites used by various US agencies.

This was the third operation flight of the Delta 4 Heavy. A successful demonstration flight was flown on Dec 21, 2004. The first operational flight was launched on Nov 10, 2007 and the second operational flight was flown Jan 17, 2009.

Delta 4 Heavy launches are the most spectacular night launches of an all liquid fuel rocket since the Apollo era with nearly two million pounds of thrust.

This was the eight and final launch for ULA in 2010, and was the 45th launch since ULA's inception in December 2006.