Complex sentence: Israeli jets had carried out hundreds of sorties against Egyptian targets by the following day, but the Egyptian SAM shield had taken a toll, and losses had mounted to three aircraft for every 200 sorties, an unsustainable rate.
Split into simpler sentences: Israeli jets had carried out hundreds of sorties against Egyptian targets by the following day, but the Egyptian SAM shield inflicted heavy losses. IAF aircraft losses mounted to three aircraft for every 200 sorties, an unsustainable rate.