JIM MIDDLETON, PRESENTER: First to the 10th anniversary of the Bali bombings.
It was a devastating moment for hundreds of Indonesian and foreign families. It was also a defining moment for Indonesia which was confronted with the ugly truth about terrorism on its own soil.
Ten years on, the authorities are still battling extremist ideology in Indonesia and the threat of further attacks.
Indonesia correspondent Helen Brown reports.
(Archival footage from the Bali bombings plays)
HELEN BROWN, REPORTER: The Bali bombings were a defining moment for Indonesia. Just a year after terrorism struck at the heart of the United States, Indonesian authorities realised they had a significant problem right on their doorstep.
(Archival footage from the Bali bombings plays, sound of explosion and people screaming)
ROSS MCKEON, BALI SURVIVOR: I still remember quite vividly, as I turned, the explosion rolling through, rolling through the club. Just a bright orange ball of flame.
(Archival footage of aftermath of bombing plays)
HELEN BROWN: For the victims, the horror of that night in 2002 has never faded.
HAYATI EKA, WIDOW (translation): I was in a very deep trauma. I was unable to tell hallucinations from reality. Let us be the last people who suffered from what they did.
JENNY DOWLING, BALI BOMBING VICTIM: It's obviously a very emotional time. It is 10 years that I've been without a brother that, my friends within the Bali group have been without their family members.
(Footage of Bali bomber's in court plays)
(Footage of Jemaah Islamiyah members training plays)
HELEN BROWN: All the leading Bali bombing perpetrators have now been executed, killed or jailed. And more than 700 members of the group behind the bombings, Jemaah Islamiyah, have been killed or imprisoned.
But at the time serious questions were being asked about Indonesia's intelligence gathering.
MICK KEELTY, FORMER AUSTRALIAN FEDERAL POLICE COMMISSIONER: We received briefings that I - you would have to say clearly did not give us confidence that, from what we already knew from the crime scene, and what was being described to us, there was no match. So it made me a little bit concerned that perhaps the Indonesian intelligence agencies had missed this.
(Footage of Indonesia's Densus 88 in training and operation plays)
HELEN BROWN: To try to ensure they didn't miss anything again, a year later Indonesia formed the counter terrorism squad Densus 88 to track down Islamic extremists. It has had considerable success. And the squad is keeping a close eye on small terror outfits which are cropping up in cities and villages across the country.
JIM DELLA-GIACOMA, INTERNATIONAL CRISIS GROUP: These groups while small, do have big plans and they do want to conduct a mass attack. But there are groups that have a lower level of professionalism and experience than those that conducted the Bali bombing in 2002, and so far they've been unable to make good on these big plans.
(Footage of arrests in Bali plays)
HELEN BROWN: In the most recent event, police arrested several people after a bomb accidentally exploded in a house disguised as an orphanage.
Authorities say the men belonged to a new terrorist cell partly inspired by Bali bombing mastermind Noordin Mohammed Top. He was shot dead by anti terrorist officers in 2009 and was thought to be behind several other large bombings in Jakarta.
But incidents like these are becoming more common and they're fuelled by a radical ideology that isn't letting up.
JIM DELLA-GIACOMA: Indonesia's been very successful in law enforcement but where it's had less success is in addressing the ideological environment or the ideas behind the violent Jihad.
HELEN BROWN: While today's violence is of a lower scale, the radical thoughts driving it are not.
And according to one progressive Muslim scholar, the ideas are reaching a dangerous stage.
ULIL ABSHAR ABDALLA, ISLAMIC SCHOLAR AND POLITICIAN: The ideology of Jihad could turn inside. I mean, it could hurt other fellow Muslims because jihad is not only killing the infidels. Jihad for them, according to the terrorist jihad, could mean also waging war against the enemy of Islam within.
HELEN BROWN: The president, Susilo Bambang Yudhoyono, has announced a new effort against radicalism. And his respected deputy, Boediono, has been asked to come up with a plan to stop violent religious ideas taking a hold.
(Footage of demonstration in Indonesia plays)
But it's a difficult task. Prisons are described as universities for charismatic jihadis who have been jailed but are now attracting criminals to the cause; people who can be rob a bank and are used to violence.
Many think the answer to prevention lies with Indonesia's youth.
DHYAH MADYA RUTH, LAZUARDI BIRRU: We have to make this country more bigger, more powerful. But we have through create or develop tolerance among our citizens.
(Footage of young leaders at event plays)
HELEN BROWN: One group sees it is already making progress. It selects young leaders from schools around the country and teaches them that tolerance is the key to Indonesia's future.
NURAINI RATNAWATI, STUDENT AND MENTOR (translation): The events are about Jihad so we mostly discuss that. And even when the event was finished we stayed in touch and discussed things, because in the training it was explained that Jihad couldn't necessarily mean war but Jihad also means studying hard and having good intentions.
(Footage of bomb going off plays)
HELEN BROWN: Ulil Abshar Abdalla was one of four prominent Indonesians targeted last year in a book bomb campaign. He's a prominent figure in the country's Liberal Islamic movement but saw firsthand the lure of jihadi language while at university.
ULIL ABSHAR ABDALLA: I can imagine why so many young people get caught in this ideology because of the gravity of the language, the gravity of ideology, of simplicity.
HELEN BROWN: The International Crisis Group foreshadowed the move to small independent terrorist cells and says it's not hard to find the places where an extreme and violent ideology is encouraged.
JIM DELLA-GIACOMA: There are very targeted communities, communities that revolve around particular mosques, schools and preachers that can be identified. And they are the communities that are at risk and where the ideas of a violent Jihad need to be addressed.
HELEN BROWN: The government's new plan to de radicalise Indonesia of extremists is meant to be implemented next year.
However, it will require an extraordinary amount of cooperation and information sharing between ministries, intelligence agencies and the police. Not an easy task in a developed country, let alone one still finding its institutional feet.
Police efforts may have seen groups such as Jemaah Islamiyah substantially weakened, but no one can guarantee there won't be more attacks.
The discovery of two houses full of explosives around Jakarta and ongoing assaults against police suggest the violence from radical Islamist groups is a long way from being diffused.
I MADE MANGKU PASTIKA, BALI GOVERNOR: As I always say, the threat is always here and there, everywhere, because it lies in the ideology, in the minds and hearts of the people who are doing this.
HELEN BROWN: Even though tourists are flocking back to Bali and there's been a full economic recovery, the island will remain on continual alert for possible terrorist threats.
But those threats haven't kept victims away from the 10th anniversary commemorations as they return to wonder how life might have turned out if they hadn't been in Bali's bar district that night.