On April 3, 2002, the Israeli Defense Forces (IDF) launched a major military operation in the Jenin refugee camp, home to some fourteen thousand Palestinians, the overwhelming majority of them civilians. The Israelis' expressed aim was to capture or kill Palestinian militants responsible for suicide bombings and other attacks that have killed more than seventy Israeli and other civilians since March 2002. The IDF military incursion into the Jenin refugee camp was carried out on an unprecedented scale compared to other military operations mounted by the IDF since the current Israeli-Palestinian conflict began in September 2000. The presence of armed Palestinian militants inside Jenin refugee camp, and the preparations made by those armed Palestinian militants in anticipation of the IDF incursion, does not detract from the IDF's obligation under international humanitarian law to take all feasible precautions to avoid harm to civilians. Israel also has a legal duty to ensure that its attacks on legitimate military targets did not cause disproportionate harm to civilians. Unfortunately, these obligations were not met. Human Rights Watch's research demonstrates that, during their incursion into the Jenin refugee camp, Israeli forces committed serious violations of international humanitarian law, some amounting prima facie to war crimes.