Israel then broke the truce on Nov. 4, raiding the Gaza Strip and killing a Palestinian. Hamas retaliated with rocket fire; Israel then killed five more Palestinians. In the following days, Hamas continued rocket fire — yet still no Israelis died. Israel cannot claim self-defense against this escalation, because it was provoked by Israel’s own violation. An armed attack that is not justified by self-defense is a war of aggression. Under the Nuremberg Principles affirmed by U.N. Resolution 95, aggression is a crime against peace.