He is Indonesia's most wanted terrorist who has "kept Jihad alive" in the world's most populous Muslim country.

Despite large-scale manhunts over more than two years, Santoso and his men have been able to evade capture, pledge allegiance to Islamic State, kill police, stockpile weapons and hold claim over territory within Central Sulawesi's dense jungle.

As thousands of military and police personnel once again scour the Poso District, AAP travelled to the remote region to get a rare glimpse into Operation Tinombala and explore how Santoso has been able to elude authorities for so long.

Santoso - also known as Abu Wardah - is the leader of Mujahidin of Eastern Indonesia (MIT), a group that emerged from the shadows of Jemaah Islamiyah (JI) - infamous in Australia as the organisation behind the fatal 2002 Bali bombings.

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Along with Daeng Koro (who was killed in a shoot out with police last year), Santoso has brought together more than 20 men and three women in Napu Valley's thick forest.

Here nearby villagers dry farmed cocoa in front of their wooden homes and dogs flop lazily onto the middle of the road.

It is quiet and life is slow, but military and police are never far off.

Multiple checkpoints have been established throughout the valley, where those passing are examined by authorities in a bid to sever supplies to Santoso.

But even with this and more than 2000 personnel on the ground, Santoso remains elusive.

The terrain is steep, the forest dense, and fog obscures vision.

More than a dozen men have died in shoot outs with the group and in March at least 10 personnel were killed when a military helicopter crashed in poor weather.

Operation Tinombala spokesman Hari Suprapto said Santoso is an expert in survival.

"One of the things we found were several betel nut trees cut down. They eat the leaves of the tree," he told AAP.

"It's like finding a needle in a haystack."

Director of the Institute for Policy Analysis of Conflict Sidney Jones said Santoso's influence stretches back to 2011 when he ran two-week para-military training courses.

"There is an alumni network of Santoso's training courses that are now spread across Indonesia and several veterans of Poso training camps are also in Syria," she told AAP.

"Even though his capture wouldn't significantly change the risk factor in Indonesia ... many people see him as the one person who has kept Jihad in Indonesia alive."

The only militant to have claim over territory, Santoso has carried out repeated attacks on authorities.

In May 2011, Santoso allegedly murdered two policemen during an assault in front of a bank in Palu, Central Sulawesi's capital, while he and his men have been linked to the beheadings and kidnapping of villagers.

Last month, the US declared him a "Specially Designated Global Terrorist" after it was revealed he had received funding from Syria.

With so much to loose symbolically, Hari doubts that if they do corner him, Santoso will want to come out alive.