WHEN AN ISRAELI bomb killed Hassan Nasrallah, the leader of Hizbullah, last week, it did not just decapitate a fearsome militia that has driven some 60,000 Israelis from their homes with frequent rocket attacks. It also dealt a hammer blow to Iran’s “axis of resistance”, a constellation of proxy forces that Iran has for decades used to attack both Israel and Western interests in the Middle East. In addition to its current assault on Hizbullah, Israel’s year-long dismemberment of Hamas in Gaza has vastly diminished Iran’s capacity to cause trouble if threatened. Those defeats, in turn, may be prompting Iran to fall back on its other main form of deterrence: its nuclear-weapons programme.