The Israel Defense Forces said its troops are “highly prepared for any scenario,” after Hamas reported the death of Saleh Arouri, one of its senior leaders, in a blast in a Beirut suburb. Hezbollah, the Iranian-backed militant group based in Lebanon, blamed Israel and said the strike will not pass “without a response and punishment.” Its leader, Hasan Nasrallah, is expected to give a speech Wednesday that may offer some indication of their plan. Israel has not claimed responsibility for the attack, but a U.S. defense official, speaking on the condition of anonymity to discuss sensitive operations, said Israel was behind the strike.