Progressive Politics

The argument is laid out in the article linked by InfustryStandard but the short of it is: As Gaza and rhe West Bank are Israeli-occupied territories, Israel doesn't have the right under international law to defend itself via military action against groups from those territories, unlike if the attack had come from—say—Lebanon. What it does have the right to do is engage in counterinsurgency effort while guaranteeing the Palestinian people's basic rights under international law. They're directly responsible for the lives of any and all civilians in the territories, and don't get to outsource that responsibility to Hamas.