SINGAPORE - Terror group Jemaah Islamiah (JI) continues to pose a serious long-term threat to the region and Singapore, 20 years after operations were mounted to cripple the network here.

Senior Minister and Coordinating Minister for National Security Teo Chee Hean gave this assessment in an interview with The Sunday Times to mark 20 years since the first wave of JI arrests, adding that Islamist terrorism remains a primary concern for Singapore.

The JI network in Indonesia continues to adapt to a more hostile security environment by evading detection, enlisting recruits and rebuilding its military capabilities, he said.

"Given its ultimate goal of establishing a Daulah Islamiah (Islamic state) in South-east Asia, the JI will continue to present a serious long-term security threat to the region and Singapore," said Mr Teo.

High-profile arrests were made recently in Indonesia, where the authorities picked up three JI operatives, including a senior official at the Indonesian Ulema Council, the country's top Muslim clerical body.

Observers have said that the JI in Indonesia - which was behind the 2002 Bali bombings that killed 202 people - has moved beyond its military aims towards taking part in the political process.

In a recent interview, Indonesian Home Affairs Minister Tito Karnavian called this renewed strategy "from bullet to ballot".

"Today, the JI is lying low. They have changed their strategy to become non-violent and more legal, but their end objectives remain - to have a syariah or Islamic state of Indonesia," he told The Sunday Times.

As Indonesia is a democracy with freedom of expression, it cannot ban a specific ideology, especially if the group propagating those ideas is not committing violence or plotting to do so.

But as long as this violent ideology remains, the threat persists, said Mr Tito, a former police chief and counter-terrorism head who investigated the JI. "We have to monitor them very, very closely, we have to strengthen our capability to monitor and disrupt them."

Vigilance is also a key message of Mr Teo's.

He said the terror threat to Singapore remains high, and the wave of extremism globally has not crested. Recent events in Afghanistan - where the situation remains "fragile and volatile" - the Middle East and elsewhere could provide more impetus for terrorist groups to grow, he said.

"The scourge of terrorism is unlikely to dissipate so long as these groups and their supporters continue to believe that violent actions and radical ideologies will allow them to achieve their objectives," he said.

The Republic's closest shave with transnational Islamist terrorism came in late 2001, as the world was still reeling from the shock of the Sept 11 attacks on the United States.

The Internal Security Department (ISD) was alerted to a member of the JI network, Mohammad Aslam Yar Ali Khan, who claimed to know Osama bin Laden and left for Afghanistan.

Its investigations uncovered ongoing plots by the clandestine Singapore JI cell to bomb multiple targets here.

The ISD moved in on the first group of JI members on Dec 8, 2001, and the work to neutralise the network would take more than a decade. It included counselling former detainees to mend their ways.

Of the 56 JI members detained since then, only four remain behind bars today - Aslam, former JI Singapore leaders Ibrahim Maidin and Mas Selamat Kastari, and Mas Selamat's son Masyhadi.

The JI episode is a "powerful reminder" to Singaporeans of the severity and reality of the terror threat, said Mr Teo. The fact that the first specific lead on the JI network here came from an alert member of the public shows that everyone has an important role to play.

Mr Teo said the lessons from the episode remain relevant for current threats such as far-right extremism, which is of growing concern. A zero-tolerance stance against any form of extremism and hatred, regardless of ideology, justifications or causes, must be maintained.

Community groups are "key bulwarks", Mr Teo said, noting that the Religious Rehabilitation Group that counsels current and former detainees has made efforts to inculcate social resilience through workshops, conferences and lectures.

He cautioned that terror attacks can happen without warning, despite the country's best efforts.

"Should an attack occur, we must remain resilient and not let it undermine our hard-won social cohesion. Ultimately, a united society is the best safeguard against extremism and terrorism," he said.