The B-52 Stratofortress is a long-range, strategic heavy bomber capable of dropping or launching the widest array of weapons in the U.S. inventory. The latest version, the B-52H, can carry up to 20 air-launched cruise missiles. The B-52 entered military service in 1954. Ongoing updates have included new avionics, data-link communications, electronic defense and offensive systems, and more powerful, fuel-efficient turbofan engines. Used in Operation Iraqi Freedom, the B-52 has been the longest-serving bomber U.S. military history.