Bernard Avishai argues that an "Iranian nuclear umbrella" won't embolden Tehran's proxies, and wouldn't do them much good anyway:
The thing is, once you understand the holes in the argument for an Iranian first strike, the idea of a “nuclear umbrella” for clients falls to the ground: strategic advantage is not a function of total blasting power; and a nuclear bomb is not a “weapon” in the ordinary sense. It is, at best, a doomsday hedge against invasion or other existential threat to a regime, which is precisely why Israel acquired one, North Korea acquired one, and Iran wants one.
But if hostilities started-up again between Israel and Hezbollah, say, Iran would refrain from using a nuclear bomb because Israel (and its ally, America) has one, too. Indeed, why didn’t Hezbollah fear Israel’s “nuclear umbrella” when it attacked in 2006? America attacked Vietnam, though its patron had a thousand bombs. Where was the Soviet umbrella?