In the year leading up to the invasion of Iraq, technocrats in Washington deployed their laptops and prepared for war. Their plans for the governing structures that would replace Saddam Hussein’s dictatorship filled bulging white papers, organizational flowcharts that spilled across thick binders, and dense memoranda for managing esoteric ministries. Israel is on the brink of testing a far different approach to regime change. Its leaders have announced a desire to dismantle the Hamas government in the Gaza Strip. Rather than entering battle with a carefully constructed blueprint for what might follow victory, though, they are winging it, improvising in the dazed aftermath of a devastating massacre that left its military and political leadership in a state of shame and confusion. Prime Minister Benjamin Netanyahu’s government announced its war aims before it had fully sketched out how it might effectively realize them. But the Israeli operation faces the same question that ultimately vexed the American project in Iraq: What comes next? Removing murderous Islamists from power solves one problem, but it creates another. Who will …