3. The benefits of escalation
A strike on Iran's nuclear complex would be at the outer boundary of the Israeli Air Force's capabilities. The important targets in Iran are near the maximum range of Israel's fighter-bombers. The fact that Iraq's airspace, on the direct line between Israel and Iran, is for now undefended is one more reason why Israel's leaders would want to strike sooner rather than later. Israel's small inventory of bunker-buster bombs may damage the underground uranium enrichment plant at Natanz, but they will likely have no effect on the Fordow mountain complex. Iran has undoubtedly dispersed and hidden many other nuclear facilities. An Israeli strike is thus likely to have only a limited and temporary effect on Iran's nuclear program.
If so, why bother, especially when such a strike risks sparking a wider war? Israel's leaders may actually prefer a wider escalating conflict, especially before Iran becomes a nuclear weapons state. Under this theory, Israel would take the first shot with a narrowly tailored attack on Iran's nuclear facilities. Paradoxically, Israel's leaders might then prefer Iranian retaliation, which would then give Israel the justification for broader strikes against Iran's oil industry, power grid, and communication systems. Even better if Iran were to block the Strait of Hormuz or attack U.S. forces in the region, which would bring U.S. Central Command into the war and result in even more punishment for Iran. Israel's leaders may believe that they enjoy "escalation dominance," meaning that the more the war escalates, the worse the consequences for Iran compared to Israel. Israel raided Iraq's nuclear program in 1981 and Syria's in 2007. Neither Saddam Hussein nor Bashar al-Assad opted to retaliate, very likely because both knew that Israel, with its air power, possessed escalation dominance. Israel's leaders have good reason to assume that Iran's leaders will reach the same conclusion.
What about the rockets possessed by Hezbollah and Hamas, Iran's proxies north and south of Israel's population centers? Israel's leaders may believe that they are much better prepared to respond to these threats than they were in 2006, when the Israeli army struggled against Hezbollah. There is no guarantee that Hezbollah and Hamas will follow orders from Tehran to attack -- they understand the punishment the reformed Israeli army would inflict. Hezbollah may now have an excellent reason to exercise caution. Should the Assad regime in Damascus collapse, Hezbollah would likely lose its most important protector and could soon find itself cut off and surrounded by enemies. It would thus be a particularly bad time for Hezbollah to invite an Israeli ground assault into southern Lebanon.
4. Managing the endgame
An Israeli raid on Iran's nuclear complex would probably not lead to the permanent collapse of the program. Iran could dig out the entrances to the Fordow site and establish new covert research and production facilities elsewhere, perhaps in bunkers dug under residential areas. Israel inflicted a major setback on Iraq's program when it destroyed the unfinished Osirak reactor in 1981. Even so, Saddam Hussein covertly restarted the program. Israel should expect the same persistence from Iran.
So is there any favorable end-state for Israel? Israeli leaders may envision a long term war of attrition against Iran's program, hoping to slow its progress to a crawl while waiting for regime change in Tehran. Through sporadic follow-up strikes against nuclear targets, Israel would attempt to demoralize the industry's workforce, disrupt its operations, and greatly increase the costs of the program. Israeli leaders might hope that their attrition tactics, delivered through occasional air strikes, would bog down the nuclear program while international sanctions weaken the civilian economy and reduce political support for the regime. The stable and favorable outcome for Israel would be either Tehran's abandonment of its nuclear program or an internal rebellion against the regime. Israel would be counting more on hope rather than a convincing set of actions to achieve these outcomes. But the imperative now for Israel is to halt the program, especially since no one else is under the same time pressure they are.
Israel should expect Tehran to mount a vigorous defense. Iran would attempt to acquire modern air defense systems from Russia or China. It would attempt to rally international support against Israeli aggression and get its international sanctions lifted and imposed on Israel instead. An Israeli assault on Iran would disrupt oil and financial markets with harmful consequences for the global economy. Israel would take the blame, with adverse political and economic consequences to follow.
But none of these consequences are likely enough to dissuade Israel from attacking. A nuclear capability is a red line that Israel has twice prevented its opponents from crossing. Iran won't get across the line either. Just as happened in 1981 and 2007, Israel's leaders have good reasons to conclude that its possession of escalation dominance will minimize the worst concerns about retaliation. Perhaps most importantly, Israel is under the greatest time pressure, which is why it will have to go it alone and start what will be a long and nerve-wracking war.