JERUSALEM — Suppose for a second that Israel strikes a cease-fire deal with Yasser Arafat: Would the Palestinian Authority president be able to control the young, fervent militants?

Arafat himself may not know for sure, as the extent of control he retains over the many military factions he has created or allowed to flourish in his territory is unclear.

On paper, the Palestinian Authority is made up of eight major security organs, each with a specific agenda. In practice, however, many of the groups compete with each other, making it difficult to maintain a clear military hierarchy and discipline — and obfuscating Palestinian Authority responsibility for each group's actions.

Complicating the scene further is the fact that there are at least four nonofficial organizations actively involved in intifada terrorism, and it is unclear to what extent they respond to Arafat's orders or signals.

They are the Izz a-Din al-Kassam Brigades, the military wing of the Muslim fundamentalist Hamas organization; the fundamentalist Islamic Jihad; the secular Popular Front for the Liberation of Palestine, a prominent faction in Arafat's PLO; and the Tanzim, a militia of Arafat's Fatah movement that in recent months has been particularly active in terrorism both in the West Bank and Israel proper.

Until the outbreak of the intifada, little was known of the Tanzim, whose Arabic name can be translated as "the organization."

A militia of some 10,000 to 40,000 Fatah supporters, the Tanzim usually recognized the authority of the Palestinian Authority in the past. In the Gaza Strip, the group was led by Ahmad Hils, but its more prominent West Bank leader was Marwan Barghouti, a veteran of Israeli prisons but also a supporter of the Oslo peace process.

The 18-month-old intifada has changed Barghouti. From a marginal local activist in Ramallah, he has become a national leader, a militant who time and again has vowed loyalty to Arafat. But he has also made it clear that he will not hesitate to carry on attacking Israelis even if Arafat orders him not to.

Indeed, Barghouti's influence has expanded to such an extent that some Israeli analysts believe that, sooner or later, Israel might prefer to negotiate with him rather than with Arafat. Others have floated the possibility of assassinating Barghouti, but the idea has been rejected.

Barghouti has reached his lofty status through violence. Some of the bloodiest recent attacks have been carried out by the Al-Aksa Brigades, a group created during the early stages of the intifada by militant Tanzim elements.

Last week the U.S. State Department officially labeled the Al-Aksa Brigades a terrorist organization — much to the delight of brigade members, who said it would induce them to increase the pace and ferocity of their attacks.

The Palestinian Authority leadership occasionally has called on Palestinians to refrain from attacks on civilians inside Israel proper — arguing that they hurt the Palestinians' international image — and to concentrate instead on attacks in the West Bank and Gaza Strip.

Yet the secular Al-Aksa Brigades have continued to engage in terror on both sides of the 1967 border, including suicide bombing. In fact, the radical Muslim organizations no longer have a monopoly on suicide bombing.

While the fundamentalist groups believe that no accommodation with Israel is permissible, members of the secular factions believe that a steady drumbeat of terror attacks alongside peace talks will force Israeli negotiators to make additional concessions.

A spokesman for the Al-Aksa Brigades told the BBC in a recent interview that the group has some 300 suicide bombers ready to attack Israelis.

Since the intifada began, secular organizations such as the Tanzim have shown close military cooperation with Hamas and Islamic Jihad, undermining the classic division many analysts used to make between the secular and supposedly moderate PLO and its "extremist" fundamentalist opposition.

The militias and fundamentalist groups complement the Palestinians' official military force, whose 35,000 to 45,000 members are divided among the security groups, intelligence groups and police forces.

Even if the thousands of armed members of groups such as Tanzim, Hamas and Islamic Jihad aren't counted, the official Palestinian forces contain far more armed men than the number stipulated in the various agreements that accompanied the Oslo peace process.

Despite their rivalries, the majority of the security bodies remain loyal to Arafat.