Hassan Nasrallah, the leader of Hezbollah, has been killed in a series of strikes on southern Beirut. Nasrallah was a global figurehead of anti-Israel resistance and had grown Hezbollah into one of the best armed non-state militaries in the world with Iran's help. The strike also killed Ali Karaqi, commander of Hezbollah's southern front. Iran and Hezbollah must now decide how to respond: fight, or backdown. Hezbollah is badly wounded and the Lebanese people are angry, creating an opportunity for more moderate voices to step in. The Israeli government has choices of its own, including a ground invasion of southern Lebanon.