The Lessons of 9/11 for October 7,

Mary Ellen O'Connell, professor of law at University of Notre Dame

October 7 is being called Israel’s 9/11. The comparison is apt for the lessons that can be learned as to the legality of launching a ground offensive to respond to terrorism. The United States and the United Kingdom invaded Afghanistan in response to 9/11. Israel has announced it will undertake a full-scale ground invasion of Gaza in the wake of Hamas’ brutal terrorism launched on October 7. The U.S. fought for 20 years in Afghanistan only to be defeated. This failure and the extraordinary ongoing suffering associated with it could well have been avoided through close compliance with authentic international law. […]

Even where Article 51 permits resort to force by a defending state, the general principles of necessity and proportionality must be met. Necessity requires that force be used only as a last resort and only when there is a reasonable chance of success. (Daniel Statman, ‘On the Success Condition for Legitimate Self-Defense’, 118 Ethics 659, 660 (2008).) The principle of proportionality requires that the force used be commensurate to the injury. Even if the U.S. had had the right to invade Afghanistan under Article 51, the invasion did not meet the requirements of necessity or proportionality.[…]

An invasion is not a last resort for Israel either. Alternatives to force exist that are all but guaranteed to succeed in ending Palestinian violence against Israel. For example, compliance with UN Security Council Resolution 242 to withdraw from territory captured in the 1967 Six-Day War. If Israelis do not have the political will to opt for alternatives that will work, the obligation of last resort is not met and conditions to resort to force under Article 51 are not met.

A full-scale invasion has no reasonable chance of success in ending violence against Israel. Article 51 is designed for a state to halt and repel occurring armed attacks. There is little, if any, evidence that Al Qaeda, let alone the Taliban, planned more attacks against the U.S. in the days or even weeks after 9/11. Rockets continue to hit Israel from Gaza; a full-scale invasion may stop them in the short run but not over time. President Biden urged Israeli leaders to learn from the mistakes the U.S. made after 9/11. U.S. defense officials consider those lessons to include the risk that Israel could make matters worse. […]

The overriding lesson of 9/11 for October 7 is that ground invasions following terrorism cannot meet the conditions of lawful self-defense. International law provides effective responses to terrorism that have led in the past to peace. They can do so again. Läs artikel