Israel-Iran alliance: Jerusalem's secret arm sales to the Islamic Republic during Iran-Iraq War of 1980

The recent history of the Middle East is complicated and complex!

Was that a smart move along the lines of the enemy of my enemy is my friend or to make the attrition between both countries more grave during this war by helping the possibly weaker side?

Probably it was short-sighted not only in hindsight!

The book author Trita Parsi is the "co-founder and executive vice president of the Quincy Institute for Responsible Statecraft [an American think tank located in Washington DC], as well as the founder and former president of the National Iranian American Council." (Wikipedia)

"... “Israel viewed its security in the region as being one in which you needed to build alliances with a non-Arab state, in the periphery of the Middle East, in order to balance the immediate neighborhood of Arab states,” said Trita Parsi, founder and former president of the National Iranian American Council and author of Treacherous Alliance: The Secret Dealings of Israel, Iran, and the United States.  ...

Clandestine Israeli sales of military equipment helped turn the tide of the war and prevent Iran from falling to Saddam’s forces, which was of huge concern to Israel at the time. ...
Israel became one of its primary suppliers of military equipment. This relationship extended beyond mere arms sales: Jerusalem also sent military instructors to Iran and, in return, received vital intelligence that proved instrumental in its own military operations. One notable instance was the Iranian intelligence that aided Israel in executing Operation Opera, the 1981 airstrike that destroyed Iraq’s Osirak nuclear reactor – a cornerstone of Iraq’s nuclear ambitions. ..."

Israel and Iran: How Jerusalem helped arm Tehran during Iran-Iraq War - The Jerusalem Post Clandestine Israeli sales of military equipment helped turn the tide of the war and prevent Iran from falling to Saddam’s forces.