She took her children and ran outside. A small rocket hit the house soon after, Kawarea said. It was apparently the final warning. Five minutes later, a larger missile hit, and the house was destroyed. According to Hamas, seven people, including three minors, were killed in the Israeli airstrike. The man the Israelis were aiming for was apparently not among those killed.
The phone call warning is part of a broader strategy. For years, the Israeli military has been using cellphone calls and small "warning rockets" — usually sent from drones — to tell people which buildings it is targeting and give them time to get out. It's a time-tested strategy for the Israeli military, and it even has a name: "roof knocking." Even if its intentions are good, however, it is a controversial tactic.
The practice dates to at least 2006. "Hi, my name is Danny. I'm an officer in Israeli military intelligence. In one hour we will blow up your house" was the call that Mohammed Deeb got shortly before his home was destroyed that year, according to Britain's Guardian newspaper. During Operation Cast Lead in 2008, the tactic was used again, with phone calls and small missiles used to warn those in buildings being targeted: The Israel Defense Forces blog later said that the airstrikes that year had adhered to the "innovative 'roof-knocking' procedure," and in 2009, Israel's Foreign Ministry said that more than 165,000 phone calls had been made to warn civilians to stay away from targets.
The logic of the tactic is obvious. Israel has long been criticized for the civilian death tolls associated with its military actions in the Palestinian territories. In theory, "roof knocking" gives civilians, and in particular women and children, a chance to escape the buildings being targeted. At worst, Israel can say justifiably say that it tried. But it's also a remarkable display of power. Both the missiles and even the telephone calls show the ease of Israel's reach, as Eyal Weizman explained in a 2012 London Review of Books article:
Israel can penetrate Gaza’s communication networks so easily because its telephone networks and internet infrastructure are routed through Israeli servers, which has advantages both for the gathering of intelligence and the delivery of propaganda.
Some critics say the tactic amounts to psychological warfare. There are reports of "warnings" that are given but no bombing following. There are also instances in which a bombing is not preceded by a warning, or, worse still, the attack may mistakenly destroy the wrong target or produce wider collateral damage – always a risk in cramped areas such as Khan Younis. Human rights groups have argued that targeting the homes of militia members violates international humanitarian law, whether warnings are made or not.
Either way, the warnings are not always heeded. According to Kawarea, after the "warning rocket" hit her house, a group of young men ran inside. It was unclear whether they thought their presence would stop the bombing or whether they wanted to be martyrs.