Identifying four different paths Tehran could take in response to Washington’s decision to jettison the 2015 nuclear agreement, Amos Yadlin and Ari Heistein recommend possible Israeli and American courses of action for each. In the two bleaker scenarios, the Islamic Republic would resume the production of highly enriched uranium that had ceased when negotiations with the Obama administration began or, worse, simply try to make a bomb. Yadlin and Heistein write:
In [the former case], the United States and Israel, in order to avoid an unintended war while still preventing Iran from acquiring a nuclear weapon, would need to demarcate a clear red line that Iran’s nuclear program would not be allowed to cross. . . . [T]he red line should not focus only on enrichment levels but also on the enrichment of large quantities of uranium to a low level or spinning a large number of centrifuges, two alternative routes that could bring Iran within a short breakout period to the bomb.
And then, there’s the worst-case scenario. Iran may adopt an extreme response to the change in U.S. policy by leaving the nuclear deal and the Nonproliferation Treaty, [which Iran signed in 1968 and has not renounced], and then breaking out to a bomb. That would raise the chances of military confrontation.
Military action to prevent the ayatollahs from acquiring a nuclear weapon would have much broader diplomatic support than in the previous scenario—in the U.S. as well as Europe. However, Israel would be well-advised to note that President Trump’s explicit promise to reduce U.S. involvement in the Middle East makes him less likely to order U.S. forces to strike. In this case, Israel would probably find itself acting alone, albeit with a “green light” and support from Washington. Israel would have to consider exercising the Begin doctrine, which calls for preventing any regime that seeks to wipe it off the map from acquiring nuclear weapons. . . .
The key for Israel, in such a scenario, would be finding ways to avoid further escalation. . . . But a surgical strike could actually provide a middle ground between inaction and escalation to full-scale war. And if Israel can obtain full-fledged and public support from Washington and endorsements in private from the Sunni Arab leadership, it may be able to deter Iran from retaliating and escalating the conflict.