A look at the three Palestinian groups responsible for the vast majority of more than 900 Israeli deaths during some 42 months of violence:

• HAMAS: Founded in 1987, it is the largest militant Islamic group. Responsible for most of the 112 suicide bombings against Israelis, it rejects a Jewish state in the Middle East. It cemented support in the impoverished Gaza Strip by running a network of social and charitable services. United States has declared Hamas a terror group and moved to cut off its funding.

• ISLAMIC JIHAD: Founded in 1979, it is a breakaway from the Egypt-based Muslim Brotherhood, guided by fundamentalist Islamic ideology and backed by Iran. Leadership is mostly in Syria. It has attacked dozens of Israeli targets, mostly through bombings and suicide bombings.

• AL AQSA MARTYRS' BRIGADES: A violent offshoot of Yasser Arafat's mainstream Fatah, it was set up after the outbreak of hostilities in September 2000. At first its militants concentrated on gunfire attacks in the West Bank, but in recent months they have carried out suicide bombings and other attacks in Israel. Some cells of Al Aqsa have begun operating more independently, with funding from Iran and the Lebanese-based Hezbollah, but the United States and Israel say Fatah and Arafat are ultimately responsible for their attacks.