If the Iran deal guarantees war–as argued by a former adviser to Israeli Prime Minister Benjamin Netanyahu–then the question is when.
It is clear that Israel has preserved its options of self-defense; it is equally clear that it has legal justification for war against Iran, given Iran’s constant threats to destroy the Jewish state, its terror attacks against Israeli targets worldwide, and its arming of terror groups in Gaza and Lebanon.
Still, the question of when Israel will attack Iran–and at this stage, it is clear the U.S. will not–depends on four key factors.
Iran’s capabilities. Iran is still relatively weak. It has no significant air defenses, its economy is struggling, and its forces are tied down in regional wars. Over time, however, Iran will become much stronger. Sanctions relief will provide cash and armaments, which Iran will also provide to Hezbollah and Hamas (or other Palestinian groups). New Russian S-300 surface-to-air missiles will complicate any attack, and Iran may soon have a ballistic missile deterrent. This factor favors an attack very soon–perhaps even before the Iran deal can go into effect.
Israel’s capabilities. Though Israel has a very effective deterrent, in the form of nuclear submarines, Israel has very limited capacity to launch an attack against Iran. Iran’s nuclear facilities are scattered, hidden, and buried, and the possible flight times and paths present great logistical difficulties. However, Israel’s capabilities tend to increase rapidly over time–as they have in the area of missile defense, which has helped it minimize rocket threats from Gaza and Lebanon. This factor favors an attack on Iran later–though not too late.
Diplomatic context. Israel is always relatively isolated in the world, which means that its wars are always short–i.e. they last until the UN imposes a cease-fire. Against Iran, Israel may be even more isolated (as President Barack Obama implied Wednesday). Therefore any war with Iran would have to be overwhelmingly effective and one-sided in Israel’s favor. That favors a surprise attack and possibly even a non-conventional attack, or one using hitherto unknown weapons. It also means Israel might wait until after the U.S. election in 2016 to strike.
Targets. A war with Iran would have at least three fronts. One would be the set of targets in Iran itself. Another would be the battle against Iran’s terror proxies on Israel’s borders (including, now, the Syrian frontier). The third would be global, as Iran attacked Israeli and Jewish targets. Israel might choose to attack Hezbollah first (and Hamas, perhaps with Egyptian help) before targeting Iran, removing Iran’s major deterrent. Alternatively, it might go beyond an attack on Iran’s nuclear facilities and try to target the regime itself in a “decapitation” strike.