Though a Muslim country, Iran is neither Arab nor Sunni - and in the Middle East, an enemy's enemy frequently is a friend. Indeed, Iran and Israel were allies until 1979. Iran sold Israel its oil. Israel had a full-fledged embassy in Tehran. The two countries enjoyed extensive business and defence ties.
Everything changed in 1979 with the advent of the Islamic Revolution. The war people fear now actually started then. Within days of the overthrow of the old, pro-Western and Israel-friendly Shah, Iran's new rulers launched a war against Israel that continues to this day.
Their first hostile act was the takeover of Israel's embassy in Tehran - few remember that episode, whose gravity was soon overshadowed by the US embassy takeover and ensuing hostage crisis. But in February 1979, Iran's first act of defiance against the international order targeted Israel. The embassy was handed over in a festive ceremony to the late leader of the PLO, Yasser Arafat, the first foreign dignitary to come to Tehran and congratulate Iran's revolutionary leader, the late Ayatollah Khomeini, for his triumph.
Khomeini's dedication to the eradication of Israel and support for the Palestinian cause went back a long way - as did his readiness to co-operate with the PLO. Indeed, the first nucleus of Iranian revolutionaries who would later become the Revolutionary Guards were trained in Lebanon under the auspices of the PLO.
After the revolution, Iran relentlessly pursued its hostility against Israel - even as it fought a bitter war along its border against Iraq.
In 1982 it dispatched 1500 Guards to Lebanon to train Shia fighters who constituted the backbone of a new organisation - Hizbollah, the party of God, which is fully integrated in the IRGC command structure.
Hizbollah's goal was to act as a proxy for Iran - and over the years it has fulfilled this goal beyond its founders' dreams. The first recorded Hizbollah suicide attack targeted an Israel Defence Forces headquarters in Tyre, Lebanon, on November 11, 1982, killing 75 Israeli soldiers and almost 30 Lebanese prisoners inside the compound at the time. Since then, Iran's Revolutionary Guards-trained proxies have made extensive use of suicide bombers.
Hizbollah used the same tactic in 1983 to murder 241 US Marines and 63 French Paratroopers who were stationed in Lebanon as peacekeepers.
When, in 1992, Israel expelled 415 Hamas and Palestinian Islamic Jihad leaders to South Lebanon after a wave of terror attacks inside Israel, Hizbollah approached them and taught them how to conduct martyrdom operations.
They soon began themselves to do so, with devastating consequences. Iran also drew them to its own political orbit, by giving both organisations US$30 million a year and allowing them to open an office in Tehran. With Hizbollah increasing its firepower and its war with Israel in the north, Iran had now acquired two new proxies which could be used against Israel.
With Israel's withdrawal from South Lebanon in 2000 and from Gaza in 2005, Iran now has effectively gained a border with Israel to conduct hostile operations - which intermittently escalate into full-fledged conflict, as they did in 1993, 1996, and 2006 in Lebanon and 2006, 2009 and earlier this year in Gaza.
Iran did not limit its assault on Israel to the region - its assassins hit twice in Argentina, in 1992 and 1994, once against the Israeli embassy and once against a Jewish cultural centre, with a combined death toll of more than 100 people. Orders came from the highest echelons of Iran's power structure and were carried out with the help of Hizbollah's top gun, Imad Mughniyeh. Suicide operations proved so successful, actually, that Iran dispatched Mughniyeh to Sudan to teach Osama Bin Laden the art of mass murder. And the rest is history.
Israel has not stood idly by and has occasionally responded in kind - Imad Mughniyeh died when his car exploded in an upscale Damascus neighbourhood in February 2008. Israel is accused of having killed Iranian nuclear scientists.
Mysterious explosions killing scores of IRGC senior commanders have plagued Iran for years.
But a nuclear Iran would cause this conflict to escalate and turn what has been largely a cold war into a very hot one. Similarly would be the case if Israel pre-emptively attacked Iran to frustrate its nuclear ambitions.
Whether such an escalation can be avoided depends on many factors, but a war between Iran and Israel is not just inevitable - it has been going on for the past 33 years - and it will continue as long as Iran is ruled by the present regime.
* Emanuele Ottolenghi is a Senior Fellow at the Foundation for Defence of Democracies in Washington DC and the author of 'The Pasdaran: inside Iran's Islamic Revolutionary Guards' Corps' (FDD Press, September 2011).
