The armed wing of Fatah, the largest faction of the Palestine Liberation Organization (PLO); set up in 1995 by PLO leader Yasser Arafat and the Fatah leadership to serve a dual function. On the one hand, acting as a semiautonomous agency, it was to engage Israeli security forces and settlers without officially breaking signed agreements with Israel entered into by the PLO or the Fatah-dominated Palestinian Authority (PA; and thereby giving Arafat a degree of "deniability"). On the other hand, as a paramilitary organization with a popular base, the Fatah-Tanzim was also to act as a counterweight to the military wing of the Islamist opponents of the PLO and the PA, namely Hamas and Palestinian Islamic Jihad. The Tanzim played a leading role in initiating and sustaining the Al-Aksa intifada.
Historical Dictionary of Israel. Bernard Reich David H. Goldberg. Edited by Jon Woronoff..