• Armed wing of Fatah, serving as the unofficial "Palestinian army"
• Has branches in every Palestinian town, neighborhood, refugee camp, and high school
• Was heavily involved in the October 2000 violence that evolved into the Second Intifada 

Established in 1995, Tanzim (which means "Organization" in Arabic) is the armed wing of Fatah, the largest faction of the late Yasser Arafat's Palestine Liberation Organization (PLO). The objective of the founders (Arafat and his fellow Fatah leaders) was to create a quasi-military force to counterbalance the escalating power of Palestinian Islamist groups such as Hamas and Islamic Jihad, which had engaged in a number of deadly skirmishes with Palestinian Authority security forces.

Tanzim acts as an informal, unofficial "Palestinian army" that can combat Israeli security forces or attack Jewish civilians without officially violating signed agreements between Israel and Palestinian authorities. Tanzim militants were in the vanguard of the violent Intifada that erupted in October 2000, when Arafat rejected the Clinton-Barak peace offer and derailed the Oslo talks. Tanzim members have been prominent in this Intifada, ambushing civilian vehicles and detonating bombs on crowded buses in Israeli cities. Tanzim also played a major role in the so-called "Tunnel Riots" of September 1996, in which its members fought alongside Palestinian policemen against Israeli security forces after the Israeli government opened a Jerusalem archaeological site to tourists.

A popular Tanzim tactic is to initiate public confrontations against Israeli security forces which become "showcase" demonstrations orchestrated in hopes of garnering sympathetic media coverage. In these rallies, hordes of civilians -- including children whose schools permit them to skip classes so they can participate -- are transported by chartered buses to Israeli Defense Force positions. In unison, the demonstrators advance defiantly on the IDF forces, throwing stones and petrol bombs in the process. Meanwhile, armed Tanzim members who are widely scattered throughout the crowd fire their guns at the Israeli soldiers. The soldiers have great difficulty returning fire at their attackers, who are protected by "human shields." If any unarmed Palestinian civilians are killed in the resultant crossfire by Israeli soldiers, Fatah and Tanzim leaders exploit the deaths for propaganda purposes.

Divided into geographical sectors that are further subdivided into cells, Tanzim has branches in every Palestinian town, neighborhood, refugee camp, and high school. Providing military training to Palestinian children and teenagers, its members are mostly men aged 20 to 35. Tanzim has also recruited a number of female suicide bombers to its cause, including 20-year-old Andaleeb Takafka, who detonated an explosive belt at a Jerusalem bus stop on April 12, 2002, killing six Israelis and injuring sixty.

Advocating the unilateral declaration of Palestinian statehood, Tanzim is unwilling to make any negotiated compromises with Israel. With an annual budget of $2.4 million, Tanzim receives its financial support directly from the Palestinian Authority (PA). Tanzim's senior commanders hold prominent posts in the PA.

The Palestinian Authority, under the terms of the Oslo agreements, promised to disarm Tanzim and rein in the organization's activities. But instead, Tanzim has continued to distribute weapons to its supporters and organized militias; distribute flyers advocating violence against Israel among Palestinians in the West Bank and Gaza; and hold regular meetings and strategy sessions with Hamas leaders. It also pressures Israel to release incarcerated Palestinians who committed acts of terror against the Jewish state.

Marwan Barghouti, who is serving a life sentence in prison for the murders of five people, is a leader of Tanzim.