Israeli military action against Iran is likely to occur but unlikely to lead to a regional war
The growth of Iran's nuclear capability means that an Israeli attack on Iranian nuclear facilities is becoming likely. However, while the repercussions of an Israeli strike would be extremely serious, such a strike would be unlikely to escalate into a regional war.
Although the US and EU remain deeply concerned by Iran's nuclear program, for Israel, the perceived threat runs much deeper. Put simply, Israeli nuclear security strategy is indelibly hardened by the experiences of Auschwitz and Treblinka. Israel regards an Iranian nuclear weapon as a precursor to a second holocaust and thus an outcome that cannot be tolerated. Indeed, unilateral Israeli strikes against an Iraqi nuclear facility in 1981 and a suspected Syrian nuclear facility in 2007, provide clear evidence of Israeli attitudes towards perceived regional nuclear threats. The Israeli government believes that even if Iran were unlikely to use a nuclear weapon, the very possession of that capability would enable Iran's leaders to wage unrestrained aggression against Israeli interests. This could either come through encouragement to allies like the Lebanese Hizbollah, directly through Iran's intelligence services, or through a combination of both.
The central point is that Israel believes that a nuclear Iran would inevitably translate as an Iran that cannot be deterred.
In practical terms and contrary to popular opinion, effective Israeli military options against Iran, though highly complex, are not impossible. The Israeli Air Force has advanced 'bunker busting' bombs capable of penetrating hardened facilities and the Israeli Air Force regularly trains for long duration, deep penetration operations. Critically important also is the fact that Israel's sunni arab neighbours are terrified of a nuclear Iran. These states may well provide logistical support to 'quietly' facilitate Israeli action.
It is true that if Israel attacks Iran, the consequences would likely be serious. In the aftermath of Israeli strikes, Iran would probably attempt to attack Israeli interests worldwide while encouraging HAMAS and Hizbollah to launch attacks against Israel from Gaza and Lebanon. In addition, Iran might attempt to close oil transit routes through the straits of Hormuz. These actions would create regional instability, civilian casualties and would cause significant economic disruption. However, at the same time, the Iranian leadership also know that if they were to engage in major retaliation- for example by attempting to ignite a regional war or using chemical weapons against Israel, this would result in an escalatory dynamic that they could not survive. Iran is fully cognizant of the fact that the US would not allow Israel's survival to be threatened and that any substantial attack on US interests would incur an overwhelming American response. While the Iranian leadership are right in judging that there exists no American appetite for a ground invasion of their country, they also understand that In the event of a war, the US Air Force has the capacity to launch devastating attacks against Iran with relative impunity.
Ultimately, both Israeli and Iranian policy will be born of distinct, changing but rational analysis.