After the successful liberation of most Iranian areas captured by the Iraqis in the first half of 1982, the situation of the IRIAF changed completely. From an air arm that was offensive by nature, it was largely relegated to air defense and relatively infrequent bombing attacks against targets of industrial and military significance inside Iraq. Simultaneously, the IRIAF had to learn how to maintain and keep operational its large fleet of U.S.-built aircraft and helicopters without outside help, due to American sanctions. Relying primarily on antiquated equipment purchased from the US in the 1970s, the Iranians began establishing their own aerospace industry.