Force 17 was formed in the early 1970s as a personal security body for Yasser Arafat and other leaders of the Palestine Liberation Organisation. It was initially based in Beirut at 17 Faqahani Street - which may account for its name. Another explanation is that the name refers to 17 Palestinian heroes killed at the battle of Karameh in Jordan in 1968.

During the early 1980s it expanded its operations to include attacks on Israelis. In 1985 it claimed responsibility for killing three Israelis in Cyprus but, according to the US state department, has not since engaged in any terrorist activity outside Israel and the occupied territories.

When the Palestinian Authority was established in 1994, Force 17 officially ceased to exist and was merged into the Presidential Security force (al-Amn al-Ri'asah) under the command of Faisal Abu Sharah. It is responsible for protecting Mr Arafat and other prominent Palestinians, as well as important installations. Other functions include intelligence and counter-terrorism, mainly against opposition activists and suspected collaborators with Israel.

According to the Israeli army, activists within Force 17 have carried out numerous anti-Israeli attacks since the start of the second intifada om September 2000.

In 2001, a senior officer in Force 17, Masoud Ayad, was assassinated by Israeli helicopters in Gaza. Israel said he had been involved in mortar attacks against army positions and Israeli settlements.

On December 4, 2001, Israel added Force 17, along with the Tanzim, to its list of "terrorist" entities. [Notes by Arab Gateway]

(Tanzim: literally, "the organisation") 

A quasi-military force set up in 1995 by Mr Arafat and the Fatah leaders to serve as a counterweight to the militant Islamic groups, Hamas and Jihad. One incident that led to this was a confrontation between Palestinian security forces and Hamas in Gaza in 1994 which left 13 dead.

A main aim of the Tanzim was to channel activity on the streets into the Palestinian Authority rather than religious extremists. Although key appointments are made by Mr Arafat, there is uncertainty about how much control he actually has.

The Tanzim is largely a grassroots organisation with local decision-making. It has branches in towns, villages and educational centres throughout the Palestinian territories. It is also seen as representing the "insiders" - ordinary Palestinians who have lived under Israeli occupation - as opposed to the "outsiders" - the exiled leaders who returned after the Oslo accords. In this role, it is sometimes critical of the PLO leadership, especially on the issue of corruption.

One of its most senior figures is Marwan Barghouti, the West Bank Fatah chief who narrowly escaped assassination by Israeli rockets in 2001 and was arrested by the Israels during Operation Defensive Shield in April 2001. 

In the earlier stages of the second intifada, the Tanzim were active in organising popular demonstrations and the Israelis accused them of instigating violence by hiding armed activists within crowds to open fire on soldiers.

The Israelis also regard the Tanzim as a tool used by Mr Arafat for exercising violence at arm's length without risking international condemnation. According to the Israeli newspaper Yediot Ahronot, in 2001 the Tanzim had an annual budget of $2.4m (£3.4m) provided by Mr Arafat.

On December 4, 2001, Israel added the Tanzim, along with Force 17, to its list of "terrorist" entities. [Notes by Arab Gateway]

Formed in October 2000, probably in the Balata refugee camp adjacent to Nablus, by Fatah supporters of the younger generation who were frustrated at the methods used by the Fatah mainstream to fight the Israelis. Its military ideas are partly inspired by the success of Hizbullah in driving Israel out of southern Lebanon, though it does not share Hizbullah’s ideology.

According to Newsday (12 March 2002), its founders were Yasser Badawi - who had the idea of forming "a very strong, fearful group" - and his long-standing friend, Nasser Awais. The two men, both charismatic figures aged about 30, became its leaders. Much of the Brigades’ support came from refugee camps around Ramallah and Nablus.

Despite the religious connotations of the Brigades’ name, they are essentially secular nationalists; unlike Hamas and Jihad, they do not seek to establish an Islamic state.

Initially, most of the Brigades’ attacks were directed at Israeli soldiers and settlers in the West Bank and Gaza. Early in 2002, the strategy changed to include suicide bombings inside Israel’s 1967 borders.

It has been suggested that this change was aimed at increasing the popularity of Fatah over the Islamist groups (Hamas and Jihad) whose suicide attacks had won them extensive support among the Palestinian public. But it has also been suggested that the change was prompted by Israel’s assassination of Raed Karmi, one of the Brigades’ leaders, in January 2002.

Other leaders assassinated by Israel are: Yasser Badawi - car bomb, August 2001, Mahmoud Titi (sometimes known as Attiti) - Israel rocket attack, May 2002; another leader was killed during an Israeli raid on Jenin in March 2001.

Attacks on Israelis during 2002 for which the Brigades claimed responsibility include:

January 27: suicide attack in Jerusalem by a female terrorist that killed an elderly man and wounded about 40 more.

March 2: suicide bombing in an ultra-Orthodox neighborhood in Jerusalem that killed nine Israelis, including six children;

March 9: suicide bombing in a Jerusalem cafe that killed 11 Israelis and wounded more than 50;

March 21: suicide bombing in Jerusalem that killed three Israelis, prompting Israel to call off ceasefire talks with Arafat’s Palestinian Authority;

21 March: Suicide bomb in West Jerusalem - at least two killed, more than 20 injured.

9 March: Suicide bomb in West Jerusalem cafe - at least 11 killed and 50 injured.

March 3: Sniper attack on an Israeli army checkpoint in the West Bank - 10 Israelis killed, including seven soldiers.

2 March: Suicide bomb in ultra-Orthodox area of Jerusalem - nine killed, 57 injured.

27 January: Suicide attack by female bomber in Jerusalem shopping area - one Israeli killed, about 40 injured.

The Brigades are not officially recognised or openly backed by Yasser Arafat or Fatah. Israel claims that captured documents show the Brigades were claiming expenses from the Palestinian Authority. In December 2001, Arafat stopped the salaries of PA employees associated with the Brigades.

Yasser Badawi’s brother, Nasser, was quoted by Newsday as saying: "The al-Aqsa Brigades were not formed by a leadership decision and will not be disbanded by their decision … The brigades were created by the people, created from the womb of the intifada, nourished and cherished by the people, and it will die only when the occupation vanishes."  [Notes by Arab Gateway]