The Dassault Mirage 2000 is a French multirole, single-engine fourth-generation jet fighter manufactured by Dassault Aviation. It was designed as a lightweight fighter based on the Mirage III in the late 1970s for the French Air Force (Armée de l'Air). The Mirage 2000 evolved into a multirole aircraft with several variants developed, with sales to a number of nations. The variants include the MDassault Mirage 2000N/D strike variant, the improved Mirage 2000-5 and several export variants. Over 600 aircraft were built and it is in service in nine countries as of 2009. There is also the Dassault Mirage 2000N which is a variant of the Mirage 2000 designed for nuclear strike. It forms the core of the French air-based tactical nuclear deterrent. The Mirage 2000D is its conventional attack counterpart.