[Sephiroth]

There's a rather interesting description of the Israel/Iran relationship at:

https://www.jstor.org/stable/10.7249/mg1143osd.7?seq=6

A selected quote:

Iran’s cooperation with Israel was not based on common fears
alone. The Shah had a rather exaggerated notion of Israeli influence in
Washington and believed that Israel could help him win the favor of
the Kennedy administration, which had been critical of his rule. 8 Iran’s
expectation of drawing itself closer to the United States through Israel
had an important role in its decision to expand ties with Israel. 9 By the
mid-1960s, the Shah had permitted a permanent Israeli delegation to
Iran that constituted a de facto embassy in Tehran. However, he did
not grant Israel more than de facto recognition, 10 and his public statements on Israel only grew more critical after the 1967 war.11 Though
Iranian popular disapproval of Israel surged, the Shah continued to
deepen relations with the Jewish state after he witnessed Israel’s victory
over the Egyptian, Syrian, and Jordanian armies. He believed that Isra-
el’s rising status would strengthen Iran’s position as a major regional
power as well.

... and ...

Israeli-Iranian Cooperation After the 1979 Revolution
Iran’s post-revolution foreign policy was at first overzealous and ideo-
logical. The revolutionaries saw the Shah’s overthrow not as a final goal
in itself but as a first step toward “liberating” the wider Middle East
from U.S. domination. The Persian Gulf’s Arab regimes, backed by
the United States, were the next stop for the Islamic revolution. The Islamic Republic focused its efforts on stirring up Shi’a populations
in Bahrain, Saudi Arabia, and Iraq. However, Iran’s efforts to over-
throw the old order were largely ineffective and in many ways counter-
productive. Faced with the threat of a revolutionary Iran, the Persian
Gulf states formed the Gulf Cooperation Council in 1981 and aided
Saddam Hussein’s military conflict with Iran.
However, much like the Shah, the Islamic Republic realized the
value of an Israeli counterweight to its Arab neighbors, particularly
Iraq. Saddam’s war against Iran became a major incentive for Iranian-
Israeli cooperation. A low-level relationship between Iran and Israel
helped the regime avoid total isolation while it benefitted from desper-
ately needed Israeli (and U.S.) weapons. Israel itself had a vested inter-
est in Iraq’s defeat, as it viewed Saddam Hussein as a central threat to
its security.