During the Iraq war there were a number of "firsts" and, true to their traditions, the U.S. Air Force was the first to get out a list of their own. The war saw the first combat use of the CBU-105 Sensor Fuzed Weapon (a cluster type bomb that releases computer controlled and radar equipped submunitions that hunt for tanks below and destroy them), CBU-107 (a guided cluster bomb), the AGM-86D CALCM (air launched cruise missile) hard target penetrator, a JDAM delivered by F-14D, and Mk-82s (500 pound bombs) delivered by B-2. The B-2 was originally designed to carry nuclear weapons and smart bombs. It had to be retrofitted to carry good old fashioned 500 pound bombs. The war also saw the first use of Compass Call (EC-130 electronic warfare aircraft) and EA-6B (navy electronic warfare aircraft) in a PSYOP (psychological warfare) role. There was the largest JSRC (Joint Search and Rescue Center in history (this was a collection of specialized troops and aircraft for rescuing downed pilots). There was also the first use of Navy F/A18 fighters as a refueling aircraft (because the air force didn't have enough aerial tankers). Also the first time four Predator UAVs flew simultaneously in support of combat operations, and the first time six U-2s flew in same theater of operations.