The ANM formed underground branches in several Arab countries, including Libya, Saudi Arabia and Kuwait, then still under British rule. It adopted secularism and socialist economic ideas, and pushed for armed struggle. In collaboration with the Palestinian Liberation Army, the ANM established Abtal al-Audah, Heroes of the Return, as a commando group in 1966. After the Six Day War of June 1967, this group merged in August with two other groups, Youth for Revenge and Ahmed Jibril's Syrian-backed Palestine Liberation Front, to form the PFLP, with Habash as leader.

By early 1968, the PFLP had trained between one and three thousand guerrillas. It had the financial backing of Syria, and was headquartered there, and one of its training camps was based in as-Salt, Jordan. In 1969, the PFLP declared itself a Marxist-Leninist organization, but it has remained faithful to Pan Arabism, seeing the Palestinian struggle as part of a wider uprising against Western imperialism, which also aims to unite the Arab world by overthrowing "reactionary" regimes. It published a newspaper, al-Hadaf (The Target), which was edited by Ghassan Kanafani.

After the eruption of the First Intifada and the subsequent Oslo Accords the PFLP had difficulty establishing itself in the West Bank and Gaza Strip. The boycott of the
1996 elections gave many the impression that the PFLP was irrelevant to developments inside Palestine. At that time (1993-96) Hamas enjoyed rapidly rising popularity in the wake of their successful strategy of suicide bombings devised by Yahya Ayyash ("the Engineer"). Also, the fall of the Soviet Union together with the rise in the Arab world of Islamism - and particularly the increased popularity of the Islamist groups Hamas and Palestinian Islamic Jihad - disoriented many left activists who looked towards the Soviet Union, and has marginalised the PFLP's role in Palestinian politics and armed resistance. However, the organization retains considerable political influence within PLO, since no new elections have been held within the organization.

As a result of its post-Oslo weakness, the PFLP has been forced to adapt slowly and find partners among politically active, preferably young, Palestinians in the West Bank and Gaza, in order to compensate for their dependence on their aging commanders returning from or remaining in exile. The PFLP has therefore formed alliances with other leftist groups formed within the PA, including the Palestinian People's Party, the Popular Resistance Committees of Gaza.

In 1990, the PFLP transformed its Jordan branch into a separate political party, the Jordanian Popular Democratic Unity Party.

When it was formed in the late 1960s the PFLP supported the established line of most Palestinian guerrilla fronts and ruled out any negotiated settlement with Israel that would result in two states between the Jordan River and the Mediterranean Sea. Instead, George Habash in particular, and various other leaders in general advocated one state with an Arab identity in which Jews were entitled to live with the same rights as any minority. Depending on the changing attitudes of the organization since then, it is unknown whether Habash intended to include all Jewish residents of Israel, or only those of Middle Eastern/Sephardi descent, as is sometimes stated in PFLP platforms, or only Jews of indigenous Palestinian ancestry.

The PFLP platform never wavered on key points such as the overthrow of conservative or monarchist Arab states like Morocco and Jordan, the Right of Return of all Palestinian refugees to their homes in pre-1948 Palestine, or the use of the liberation of Palestine as a launching board for achieving Arab unity - reflecting its beginnings in the Pan-Arab ANM. Today, the PFLP is less staunch in its opposition to a negotiated solution than it was in 1987, when the First Intifada broke out, but generally maintains a hardline profile. Its Abu Ali Mustafa Brigades has been active during the Second Intifada, with attacks on soldiers, settlers and regular civilians, both on the Occupied Palestinian Territories and inside Israel proper.

This is a list of armed attacks attributed to the PFLP. It is not complete.

The PFLP's Abu Ali Mustapha Brigades has carried out attacks on both civilians and military targets during the Al-Aqsa Intifada. Some of these attacks are:

The killing of Meir Lixenberg, councillor and head of security in four settlements, who was shot while travelling in his car in the West Bank on August 27, 2001. PFLP claimed that this was a retaliation for the killing of Abu Ali Mustafa. ISRAEL AND THE OCCUPIED TERRITORIES AND THE PALESTINIAN AUTHORITY. Without distinction - attacks on civilians by Palestinian armed groups, Amnesty International, July 11, 2002.

The 21 October, 2001 assassination of Israeli Minister for Tourism Rehavam Zeevi, the only Israeli politician to have been assassinated in the current intifada.

A suicide bombing in a pizzeria in Karnei Shomron, on the West Bank on February 16, 2002, killing three Israeli civilians.

A suicide bombing in Ariel on March 7, 2002, which left wounded but no fatalities.

A suicide bombing in a Netanya market in Israel, on May 19, 2002, killing three Israelis. This attack was also claimed by Hamas, but the Abu Ali Mustafa Brigades have identified the perpetrator on their website as one of their members**

A suicide bombing in the bus station at Geha Junction in Petah Tikva on 25 December, 2003 which killed 4 Israelis. *

A suicide bombing in Bikat Hayerden on May 22 , 2004 , which left no fatalities. *

A suicide bombing in the Carmel Market in Tel Aviv on November 1, 2004 , which killed 3 Israeli civilians. *