The Challenger 1 main battle tank originated from an Iranian order to improve the Chieftain line of tanks. However, due to the Iranian Revolution, the project was scrapped, which prompted the British Army take over as the customer. They tasked its designer, the Military Vehicles and Engineering Establishment, to further develop the tank in order to meet Western European requirements. The "Challenger" was initially called the "Cheviot." It officially entered the British Army in 1983, and was instrumental during the Persian Gulf War. In the year 2000, the British Army phased out its line of Challenger 1 tanks. Majority of these tanks were sold to Jordan, where they call it the "Al Hussein."