The Titan IV family (including the IVA and IVB) of space boosters were used by the U.S. Air Force. They were launched from Cape Canaveral Air Force Station, Florida, and Vandenberg Air Force Base, California. At the time of its introduction, the Titan IV was the "largest unmanned space booster used by the Air Force."The Titan IV was the last of the Titan family of rockets. It was retired in 2005 due to its high cost of operation.