Conceptually, the Lavi had its origins in the idea espoused by IAF commander and Minister of Defence Ezer Weizman that Israel's combat aircraft should fall into 'two-tiers' – a small number of high performance aircraft and a larger bulk with less sophistication and complexity. In the mid-1970s, the plane that was to become the Lavi was meant to be a multirole fighter-bomber to replace aging IAF aircraft such as the Douglas A-4 Skyhawk and IAI Kfir; however continuous revisions of the proposed aircraft led to the incorporation of more advanced technologies and ideas to produce an ambitious aircraft[4] in the class of the American General Dynamics F-16. The IAF was estimated to have a requirement for 300 aircraft, 60 of which were expected to be combat-capable two-seat trainers.[5]