We are on our way to a place the Israelis call 'the capital of terror' - Jenin. Half of all suicide bombers who have penetrated Israel have come from Jenin and its surrounding villages. To stop the deadly attacks, Israel has sealed most of the West Bank. And as we head deeper into Palestine, we are told by the Israeli soldiers that we cannot go on. Eventually, we break the blockade by taking a series of back roads, and a day later we arrive in the village of Aqqaba, near Jenin. Aqqaba is home to one of Palestine's most famous martyrs - Izzedine Masri. Izzedine left here a month ago, to carry out a gruesome deed. Strapped with explosives, he made it to Jerusalem and blew himself up, killing 15 Israeli civilians including six infants at a pizza restaurant in the city centre. Izzedine Masri came from one of the wealthiest families in the village. His father, Abu Ayyad runs a successful restaurant in Jenin. Although he approves of his son's martyrdom, both parents are still in the state of disbelief.

ABU AYYAD, FATHER (Translation): It was a huge surprise. It was a shock and we're still suffering from it. One's child is always precious. They say he'll go to heaven and we believe in God, which comforts us somewhat, not because he's gone, but in the hope that he is in heaven. It's still a shock for us. It came down on us like a bolt of lightning. The most hurt are me and his mother.

FATIMAH AYYAD, MOTHER (Translation): I didn't expect him to do this. He didn't behave differently or give the faintest sign. Suddenly everyone at home started screaming. I lay all the blame on Sharon and Arafat and other leaders, who haven't found a solution to this problem.

But Izzedine did fit the profile of a suicide bomber. He was young, 23, contained and calm, right up until he pulled the trigger. And this is what worries Israel. It's the seemingly normal young men, who in greater numbers than ever before, are choosing this option. It's no longer just the domain of religious fanatics.

ABU AYYAD (Translation): He was a very sensible and well-mannered boy and religiously sound. He'd go from work to home, and from home to the mosque. He was a quiet young man. He was very good. He was nice to his parents, his siblings and to people in general.

While the whole village and the family bask in the glory of Izzedine's martyrdom, his mother Fatimah is probably the only person in the village who does not endorse her son's attack. For her, it's difficult to understand that her son packed himself with nails and explosives and then took his life, to murder 15 innocent civilians and injure 90 more.

FATIMAH AYYAD (Translation): I feel and sympathise with them. Before I learned that it was my son, my younger children called me to watch it on TV. When I saw those people, I felt sorry for them because it's not their fault. We didn't expect him to be our son and only found out around 6:30 or 7:30pm. We found out after the evening prayers. When I knew it was my son, I felt even sadder. We do not wish this on people, either them or us.

But around here, they're proud of what Izzedine Masri did. His short life has been glorified. And it's not hard to find others who want to follow his example.

YOUNG MAN (Translation): Of course, many young men take him as a role model and hope to become martyrs and be part of the resistance and blow themselves up defending Jerusalem and Palestine and the soil of the nation. Many young men seek this martyrdom because it's accepted by God and has no judgment.

These two say they are considering enlisting as suicide bombers. For them it's not about international terror, like destroying New York's twin towers. It's about fighting Israel. Almost a year into the Intifada, Palestinian stones and gunmen provide no answer to the might of the Israeli army. To an outsider, it's an unthinkable act, but they have come to the conclusion that suicide attacks are the only effective weapon against Israel.

YOUNG MAN (Translation): We have no other way to resist but this one. There are guns and machine guns but the best and most guaranteed means is to do yourself in, to blow yourself up.

From Aqqaba, it's about 20km to Jenin - the place where martyrs are made. During the first Intifada in 1987, Jenin was a stronghold of Fatah, Yasser Arafat's political party. Arafat promised the Palestinian people a state. But when he failed to deliver, many turned to the radical Islamist parties like Hamas and Islamic Jihad. And the problem for Israel is their support is growing every day. Since the beginning of the current Intifada, these parties have doubled their support right across the West Bank and Gaza. Most Islamist leaders in Jenin have gone underground. But on the third attempt, we secure a rare interview with a senior Islamic Jihad operative who calls himself Marwan.

MARWAN (Translation): Islamic Jihad carried out a few attacks in this Intifada that focused attention on Islamic Jihad. This, and especially suicide operations, attracted people.

As an Islamic Jihad leader who is promising more suicide attacks, it's no surprise the Israelis want Marwan dead. He's constantly on the move, changing cars and locations to avoid assassination.

MARWAN (Translation): Many are willing to become martyrs and neither Jihad, Hamas nor any other organization can accommodate all those who want to be martyrs. There are always people who want to be martyrs, but no organization or group can take all of them.

Last week, with all eyes on America, Israeli forces moved into Jenin. Israeli PM Ariel Sharon called Yasser Arafat 'Israel's bin Laden'. Electricity, telephones and water were cut. Three Palestinians were killed and 11 more were injured. But last night, the siege of Jenin was lifted.

We are on our way to Nablus, the other stronghold of Palestinian resistance, to examine what the Palestinians call state terrorism, the Israeli assassination policy. To get there, we have to access the West Bank and try to come in further south. The day we arrive in Nablus, there's been an assassination attempt on senior Fatah military commander Jihad Musseme. It's almost a daily occurrence here, though the attempts are not always reported in the international media. Musseme survived the attack, only because he managed to drag himself from his burning car before a second missile demolished it.

JIHAD MUSSEME (Translation): I want to tell Peres and Sharon that the Palestinian people will be steadfast, continue to resist and won't be scared by the Zionist and American destruction machine. Their actions only reinforce our resolve and steadfastness.

One of Israel's biggest hits was here in Nablus on the 31st of July. Two American-made Apache helicopters struck with rockets at the Hamas office in this residential building. Two senior Hamas leaders were killed along with six civilians. Sharon said this was a preventative strike against terror and would serve to protect his people. But just the opposite happened. This was the trigger for Hamas to send Izzedine Masri to the Jerusalem pizza parlour.

To the world, the Israelis sell their assassination policy as pinpoint preventative action. But it's not very accurate. 17 out of 60 killed so far, have been innocent bystanders. On the day of the Nablus assassination, Nadia and Adul Mummen's two sons were waiting to see a doctor on the floor below the Hamas office. When the rocket struck, Bilal, 10, and Ashraf, 6, were killed instantly.

NADIA MUMMEN, MOTHER (Translation): My heart was wounded from the inside when I knew my sons were martyred. I felt sadness. I felt very sad for them when I knew they were martyred. They were my only sons and they both died together.

Neither Abul nor his family are political. They were good friends with an Israeli family with whom they shared a business. This will no longer stand as an example of how Palestinians and Israelis can live in peace.

ABDUL MUMMEN, FATHER (Translation): I used to work in Israel and my partner was Jewish. I worked and lived with Jews more than I lived with Arabs. In the end, they came and killed my babies. It shows that all Palestinian people here are targeted - all Palestinians, whether demanding their rights or just hanging on to their land, are targeted and Israel intends to kill them.

These are the militants the Israelis have tried to suppress by killing their leaders. The Palestinian martyr industry has been working overtime. Giant posters of the Hamas leaders who were killed in the Nablus raid - Jamal Mansur and Jamal Salim - take centre stage. The day is being held in their honour. Assassinating them has amounted to a call to war. Now as martyrs, they are used to whip-up support for the Intifada and hatred of Israel. Hamas and Islamic Jihad proudly display their suicide bombers in waiting. The climax of the day is a pledge on the Koran.

MASS PLEDGING SESSION: Say brothers, "I swear by almighty God. I will resist and struggle against the Israeli enemy with my soul and my money and my words, even if it leads to my martyrdom to avenge the souls of the martyrs. Jihad is our way and to die for God is our paramount wish.

In a show of unity, gunmen parade their wares. Sharon's assassination policy has only served to deepen resistance and unite all the Palestinian factions.

MASKED YOUNG MAN (Translation): These people must continue to the end. This has enhanced our national unity and cohesion. As you can see, Fatah, Al-Kassam Brigades and Islamic Jihad are united and have pledged to avenge the martyrs' blood and to continue the struggle until Jerusalem, Palestine's eternal capital, is liberated.

But much of the popular anger is reserved for their own. For the Palestinian who betrays the cause and works with the dreaded Israeli secret service, the Shin Bet. Every successful assassination needs a Palestinian collaborator on the inside to provide the precise time and place to strike. This video was secretly filmed. It's the execution of a Hamas collaborator. The information he provided to the Shin Bet led to the death of two of his colleagues. Although Yasser Arafat has put a temporary halt to executions like these, seven collaborators are still waiting on death row. To hinder the Israeli assassination campaign, the Palestinian Authority has intensified its hunt for collaborators, recently arresting 100 in the Nablus area alone. Mahmoud, not his real name, is one of them. He was providing the Shin Bet with information on a Hamas and Fatah activist.

MAHMOUD (Translation): I did, actually...I did watch those people. And then, and then I gave him full information about them.

Mahmoud has been working for the Shin Bet for about two years. He has lived in Nablus and in Israel. In Israel, Mahmoud had an extensive criminal record for theft and drug offences. Mahmoud says the Shin Bet told him they were going to jail him for life if he did not work for them. It's likely Mahmoud will not be executed because he has cooperated fully with the Palestinian Authority.

MAHMOUD (Translation): After the interrogation finished, the interrogator thanked me and said that although I'd made a mistake, at the same time I'd helped them a lot because the people I was watching were meant to be assassinated. He said they were able to save them before they were harmed.

But it's Mahmoud's family who will pay the biggest price for his betrayal. They live here on the outskirts of Nablus, and they do not know the real reason for his arrest. But the family will become known as a collaborator family. They will be ostracised and cast out of the community.

MAHMOUD (Translation): I'm ashamed even to look my parents in the eye. I'm ashamed to look at them, and my wife. If I ever get out of jail, I won't go to my parents' home. If I get out of here, I won't see anyone, because I can't look anyone in the eye.

Back in Israel, Prime Minister Sharon's policy to hit back harder doesn't appear to have won the war. An unprecedented number of suicide bombers - 67 according to the army - have brought their deadly wares into Israel. The army says they have no choice but to act against the suicide bombers.

OLIVIER RAPOVITZ, ISRAELI DEFENCE FORCES SPOKESPERSON: We're not going to wait to have new victims - children, woman, just people - and then to act. If the Palestinian Authority is not capable or maybe refused to arrest these people, to stop the terrorist process, we have no other choice but to act in order to protect ourselves. I would say it's a self-defensive measure that all the world, I believe, can understand.

And as the defence force plans for a campaign until 2006, it will rely more heavily on the Shin Bet. Moshe Kuperberg was a senior Shin Bet officer in charge of recruiting Palestinian agents and collaborators. He was also an investigator and interrogator, who retired from the service in April 1999.

MOSHE KUPERBERG, FORMER INTELLIGENCE OFFICER: The intelligence to my mind is the most important thing, is the most important thing, because it feeds the military one and the political one. It gives them the information they need in order to achieve some agreements or assassinations.

REPORTER: It's crucial?

MOSHE KUPERBERG: It's crucial. With no intelligence, there's nothing you can do.

The Shin Bet has been conducting an unseen war in the occupied territories. These pictures offer a rare glimpse of the agents at their deadly work. They come from the security service's own website. Here, they are arresting suspected Palestinian militants. Agents go undercover, immersing themselves in Palestinian communities, speaking Arabic and dressing as Palestinians. They recruit and manage a huge network of Palestinian collaborators.

MOSHE KUPERBERG: Some groups like the Fatah, Hamas, Islamic Jihad, the Popular Front, the Democratic Front, we consider them to be nests of terror. In order to prevent this terror, you have to do many things. One of things you should do is to penetrate them, learn them, know who are their agents, where do they hide or keep the ammunition and the explosives. Who is helping them, who is serving them here. What are their means and the ways of communications? Who is supporting them financially? You will not know it by, you know, dreaming at night. You should be within them. And it is better that your agent will be consider or will serve in one or more of those terror nests as an active member. And then you can act.

REPORTER: And did you have good success at this?

MOSHE KUPERBERG: Personally? Or as a...

The overall policy of Shin Bet?

MOSHE KUPERBERG: They have wonderful success.

A collaborator we spoke to claims Israel has 15,000 Palestinians working for the Shin Bet. Moshe Kuperberg says they have Palestinian spies in the senior leadership of every Palestinian faction.

REPORTER: When you penetrate an organisation, how deep can you get?

MOSHE KUPERBERG: To the top.

REPORTER: Really? You have been all the way to the top?

MOSHE KUPERBERG: All the way to the top. When I mean to the top, I don't mean Mr Arafat, but definitely to the top.

REPORTER: And have those people obviously not been revealed? Or are they still work...

MOSHE KUPERBERG: Some of them have been revealed. And all the others are not to be discussed here.

This illustration shows how the Nablus assassination of eight happened. First an Apache marks the spot with a laser, and the second delivers the rockets. But the crucial information - the location of the human targets - was provided by a Shin Bet operative and his collaborators on the ground. In this case, the collaborator was a Hamas activist. Kuperberg's colleague, Shimon Romah, who was head of the Shin Bet in the West Bank until 1993, explains the deadly precision of such operations.

SHIMON ROMAH: If you want to, how you call it? Liquidation - if you want to liquid somebody, you have to have exact information about when he's leaving his place, with what car, in which direction, who will be with him - all these details. And you have to cover him very, very good because you need to be in a certain place in a certain time. I mean, every second counts and every road counts. So, you have to be perfect.

Israel justifies its assassination policy on two grounds. It claims the policy minimises both Israeli and Palestinian civilian casualties and acts as the first line of defence against terrorist attacks.

MOSHE KUPERBERG: We also have some, you know, proof that we eliminated lots of terror acts by using this policy. It does not mean that terror acts will not happen again. But this is, you know, it's fighting with a snake that everybody - you know, you cut the head and it grows again. You cut the head and it grows again. That's it.

SHIMON ROMAH: We know that we are under the criticism of the media and the political world all over. And we still go on with it. Now, knowing that we will reconsider...every time we will know that there are civilians there, because we know that the minute that we will exaggerate with these operations by killing civilians, we will, in a way we will shorten our ability to continue with this policy.

There are those within Israel who argue against the policy of assassination. Jessica Montell is executive director of B'Tselem, an Israeli human rights group. She argues the assassinations are nothing more than extrajudicial killings where the defence forces act as judge, jury and executioner.

JESSICA MONTELL, EXECUTIVE DIRECTOR B'TSELEM: There's no official statements about the person, no presentation of evidence before or afterward in any sort of judicial process.

She's also highly critical of Shin Bet's recruitment methods.

JESSICA MONTELL: Israel pressures Palestinians to collaborate, both in torture and interrogations. Pressure on family members to get other family members to collaborate, refusing to give Palestinians to work in Israel, permits to travel abroad. I mean, any permit that you need from Israel, the General Security Service could make that conditional on you providing information to Israel.

We don't know why Palestinian Rami Barhm chose to work for the Shin Bet, but he did for 28 years. He now represents 1,700 collaborators, who for their safety, have been relocated to Israel. Rami wants the Israeli government to give collaborators citizenship and compensation.

RAMI BARHM (Translation): The state of Israel could not have existed and would not be able to exist without those collaborators. It's a clear cut case.

Rami and his community of collaborators live here in this Jewish settlement, north of Jerusalem. They are a lost community, rejected by all. Like Rami, a few have been given new identities, but most live in fear.

RAMI BARHM (Translation): It's an unbearable situation from all aspects. There are some who have food, but are still suffering from other aspects. But as for those collaborators, their condition is very bad.

INTERPRETER: What do you mean? In what way?

RAMI BARHM: In all aspects - economically, socially, safety wise, family wise and so on. When I say in general, I mean in all ways.

Many of the collaborators have been forced back into Palestinian areas to work for the Shin Bet again. They are marked men as Palestine is conducting an assassination program of its own.

BASSEM ABU SHARIF, ARAFAT SPECIAL ADVISER (Translation): They were covert operations for Palestinian intelligence because these people were very dangerous and they were leading their operations of spying and passing information from the areas under the protection of the Israeli army. So there had to be some covert operations to liquidate these people because of their dangerous and criminal participation in the killing of Palestinians.

With such a dirty war on both sides, it's difficult to see how last night's ceasefire can be maintained. The Palestinian uprising has turned moderates into radicals, and hardened the Israelis against a negotiated peace. But both sides have responded to efforts by the United States to build a worldwide coalition against terrorism. And if last week's horror in America can achieve this and bring them back to the table, then something good will have come out of last week's catastrophe.