In 2000, the IDF ingloriously withdrew from Lebanon, leaving in the lurch its erstwhile allies from the South Lebanese Army. That was the end of a political love affair, going back decades into the past, between Israel and Christian factions in Lebanon. The scenes of Israel’s Arab allies, rushing to the border as refugees with their meager belongings, smacked of defeat, faithlessness, even betrayal.“I would like to beg your forgiveness,” wrote a former IDF intelligence officer to his Lebanese colleagues, “for convincing you to cooperate with a nation of traitors.”Just like in any broken love affair, bonds of fondness were replaced with anger. On the Israeli side, many blamed the South Lebanese Army for the Israeli predicament in Lebanon. This affair, now all but forgotten, uncovered a problematic dynamic in Israeli regional policy. Now, with the advent of the unofficial Israeli-Saudi cooperation, its lessons are more important than ever.There are two interlinked problems in alliances between Israel and various regional forces or minorities, whether in Lebanon, South Sudan, Iraqi Kurdistan or elsewhere. First, the Israeli side invested too much emotion and hope in such volatile relations. Even worse, Israeli military and civilian officials leveraged such alliances too often for excessive, almost megalomaniac goals. Anyone who follows the press discourse about the Iraqi Kurds today, or the South Sudanese a few years ago, will recognize immediately the naive romanticism reminiscent of the bygone love affair with the Lebanese Christians. They are true friends of Israel, a noble minority in the Middle East. Just like us, they are brave, daring, creative people “whose only friends are the mountains.” Stories of daring Mossad operations, of clandestine cooperation, strike a chord with Israeli sensitivities. Who wouldn’t like to think of one’s country as a beacon of light, the champion of minorities persecuted by Israel’s own enemies? In the 1980s, such romanticism tempted Israeli policy makers to put excessive trust in Lebanon’s president Bashir Gemayel and his Phalanges. The result was a botched “peace agreement” that disappeared without a trace. More recently, African hands in the Israeli Foreign Ministry were surprised and dismayed when South Sudan, also portrayed romantically in the press as a brave, pro-Israel and freedom-loving country, blew apart in a tribal civil war of all against all. Now, Kurdish romanticism, all too fashionable in Israel, blinds too many to the structural weaknesses, poor policy and endemic corruption of the Kurdish regional government in Iraq.Moreover, instead of cooperating carefully with regional partners, Israel had a tendency to leverage such alliances to achieve unrealistic or excessively risky goals. In the case of Lebanon, instead of supplying the Christians from across the border, Israel relied on their cooperation to invade the country and enforce “a new order” in the Land of the Cedars. This decision did not only implicate Israel in atrocities committed by its allies, such as the Sabra and Shatilla massacre, but also bogged it down in a redundant, bloody war for almost 20 years.Alarmingly, one can recognize similar tendencies in Israel’s tightening, yet strictly unofficial, alliance with Saudi Arabia. Indeed, the Middle Eastern web of interests and the Israeli-Iranian cold war align the interests of the Jewish State and the Royal House of Saud. Both are enemies of Iran, and in the regional game of thrones, the enemy of my enemy can sometimes be my friend. Cooperation with Saudi Arabia and its new ambitious crown prince, Mohammad bin Salman, is therefore expedient – yet Israel has to take special care to avoid past mistakes. First of all, the warming (though secret) cooperation should not blind us to the adventurous nature of Saudi policy. While bin Salman is certainly ambitious and brave, his foreign and domestic policies are reckless at best. As for now, his army is bogged down in an endless, mostly failed war against Shi’ite tribesmen in Yemen. Connoisseurs of Middle Eastern history may draw parallels with Egypt’s previous involvement in the same country. It didn’t end well then, and it is probably not going to end well now.In the Cold War against Iran, Saudi Arabia’s score is also unimpressive. The boycott against Qatar did not succeed, while Lebanon, Iraq and Syria are gradually falling under Iranian dominance. The Saudis seem so desperate, as to bully their own allies, such as former Lebanese prime minister Saad Hariri, still held in Riyadh under dubious circumstances. The domestic policies of the crown prince may succeed, but they may also lead the country to a Saddamite tyranny, destabilization or collapse.The greatest danger for Israel here is the temptation to overreach with this alliance. Take the Lebanese example. Following the retirement and disappearance of Hariri, Saudi Arabia and Lebanon are on the brink of hostilities, but the Saudi Army probably cannot strike Hezbollah in Lebanon. Israel, however, can do such a thing, and the Saudis would love to see Netanyahu pulling the chestnuts out of the fire for them. They may offer money, or write alluring promises on ice. Most probably, Riyadh hopes to provoke Hezbollah to attack Israel, tempting the Jewish state to counterattack in response. However, when things go wrong in Lebanon, as happens all too often, the Saudis will wash their hands of the whole affair, which was secret to begin with, and even condemn Israel for its “aggression.”To sum up, cooperation with Saudi Arabia fits well with Israel’s strategic position, but as long as the Saudi side keeps the relationship secret, Israel’s contribution has to be secret as well. Intelligence cooperation, strategic coordination, even clandestine operations are welcome – but Israel should not fight wars on Saudi Arabia’s behalf, nor indulge in daydreams that this alliance might completely reverse Iranian gains in the Middle East. Nor can we look forward to a formal alliance or a peace agreement with Saudi Arabia without considerable progress in the Israeli-Palestinian peace process. As for now, we have unofficial coordination with a volatile regime, holding a very mixed record of successes and failures. Nothing more.The writer is a military historian and senior lecturer in the History and Asian Studies Departments, the Hebrew University of Jerusalem.