Continuous relationship since 1978 — Camp David
There were relations before 1978, and one of them ended in a war. But the continuous, structural relationship — the one with a budget line — begins with the accords of September 1978 and the treaty of March 1979, when the United States undertook to fund both parties to a peace it had brokered. Everything since sits on that appropriation.
The Egyptian relationship is the Israeli one's mirror image and its origin: the same negotiation at Camp David produced the aid to both, and for forty years the two appropriations have moved together. What is documented: the 1956 withdrawal of Aswan Dam financing that precipitated the Suez war; Sadat's expulsion of Soviet advisers in 1972 and the realignment that followed; Camp David and the 1979 treaty; $1.3 billion a year in Foreign Military Financing, fixed since 1987; the forgiveness of $7.1 billion in military debt in 1990 for joining the Gulf coalition; and the 2013 suspension of major weapons deliveries after the coup and the Rabaa killings, lifted in 2015. The standing structure is aid as the instrument that holds a peace, and the open question is what four decades of it has done to the recipient. The ruptures ran both ways.
This page covers structure, not sentiment. Egypt and Israel share a page of origin — Camp David — and the section is built so the two can be read together. Neither is the other's footnote.