Israel also provided military instructors during the war, and in turn received Iranian intelligence that helped it carry out Operation Opera against Iraq's Osirak nuclear reactor.
[5] Iran's hostility led to an escalation of rhetoric between Ayatollah Khomeini and Iraqi President Saddam Hussein, a Sunni who advocated for secular pan-Arab nationalism.
He reached out to the U.S. government for military arms to help consolidate his position; however, the Carter administration chose not to become involved in Iran's internal affairs.
[11][12]: 94 Unable to get military equipment from the Carter administration, the Iranians reached out through back channels to the Israeli government and negotiated a preliminary covert arms deal between the two countries.
[18] Iranian officer, Mohammad-Reza Aminizadeh, chief of the first battalion of air ground forces who sought political asylum in England in 1985, described in an interview with London-based magazine Al-Dastur his observation of the first contacts between Israel and Khomeini's government.
Three days after mission returned to Tel Aviv one airline cargo flew to Larnaca and brought Phantom or F-14 parts, 'Tom Cat', and since then the relations developed so that besides arms, medicine, chicken, eggs, and foodstuffs were also exported to Iran.
[21][22] Around the same time, other Israeli-owned military supplies were being clandestinely shipped from European storage locations to the Iranian ports of Chabahar, Bandar Abbas, and Bushehr.
In the spring of 1982, after it was determined that Israeli Defense Minister Ariel Sharon was violating the agreement, the Reagan administration rescinded its consent for the sale of any American related military equipment by Israel to Iran.
[29] Israeli arms sales to Iran totaled an estimated $500 million from 1981 to 1983 according to the Jaffe Institute for Strategic Studies at Tel Aviv University.
[12]: 107 According to Ahmad Haidari, an arms dealer who worked for the Iranian government, "roughly 80 percent of the weaponry bought by Tehran immediately after the onset of the war originated in Israel.
"[12]: 106 The fact "that the Iranian air force could function at all", according to Mark Phythian, after Iraq's initial attack and "was able to undertake a number of sorties over Baghdad and strike at strategic installations" was "at least partly due to the decision of the Reagan administration to allow Israel to channel arms of US origin to Iran to prevent an easy and early Iraqi victory.
[36] Yaakov Nimrodi, who was Israel's military attaché in Tehran from 1955 to 1979, similarly in July 1981 signed an arms deal with Iran's Ministry of National Defense.
[37] In March 1982, The New York Times cited documents indicating that Israel had supplied half or more of all arms reaching Tehran in the previous 18 months, amounting to at least $100 million in sales.
[4][33]: 174 Ariel Sharon, Israel's defense minister, was the first to publicly disclose Israeli sale of military equipment to Iran during his visit to United States in May 1982.
[4] Similarly in 1984, one of Israel's many European arms dealers, who was based in Sweden, shipped hundreds of tons of explosives and dynamite worth over 500 million Swedish kronor by way of Argentina to Iran.
[12]: 110–126 The Iran–Contra Affair began in late 1984 when representatives of Israel and Iran met to discuss ways of opening an arms channel with the United States for sophisticated American-made weapons.
Ghorbanifar said there were Iranian officials who sought a more pro-Western orientation and sales of sophisticated American-made weapons would help gain sway for them with Ayatollah Ruhollah Khomeini.
[4][37] On 7 June 1981, a squadron of Israeli Air Force F-16A fighter aircraft, with an escort of F-15As, bombed and heavily damaged the Osirak nuclear reactor in Iraq.
Political scientist Dan Reiter has argued that if Osirak had not been destroyed, Iraq would have become a nuclear state and Saddam would have taken over a large chunk of Iranian territory, as well as Kuwait.
[39]: 17 Gerard Beau, a journalist for Luxembourg RTL, who was at the front line when the war broke out between Iran and Iraq, wrote that in 1980 around 350 Israeli technicians were working at Iranian airbases to help in the operation of F-4, F-5, and F-14 jets as well as train local specialists.
[47] There were never less than around one hundred Israeli advisers and technicians in Iran at any time throughout the war, living in a carefully guarded and secluded camp just north of Tehran, where they remained even after the ceasefire.
Newsweek reported that after an Iranian defector landed his F-4 Phantom jet in Saudi Arabia in 1984, intelligence experts determined that many of its parts had originally been sold to Israel, and had then been re-exported to Tehran in violation of U.S.
The Iranian government after the revolution faced significant difficulties selling oil to international markets as most European companies left Iran.
[36] Trita Parsi writes that Israel supplied Iran with arms and ammunition because it viewed Iraq as a danger to the peace process in the Middle East.
[12]: 108 According to David Menashri of Tel Aviv University, a leading expert on Iran, "Throughout the 1980s, no one in Israel said anything about an Iranian threat – the word wasn't even uttered.
"[12]: 104 Parsi explained in an interview with Diane Rehm that despite the anti-Israeli rhetoric publicly displayed by Iran, in actuality, the two nations secretly depended upon the support of one another to face the formidable opposition of both Iraq and the Soviet Union.
He cites as evidence the fact that this relationship endured despite the ramped-up rhetoric that was brought about by the Islamic Revolution in Iran, up until the collapse of the Soviet Union and destruction of the Iraqi military by the U.S. in the Persian Gulf War, both in 1991.