SINGAPORE — Countries in the region had “underestimated” the threat of Marawi — the southern Philippines city engulfed in a bloody battle between militants and government forces last year — and such a situation “must never happen again” in South-east Asia, said Defence Minister Ng Eng Hen on Saturday (Oct 20).

At the height of the crisis in June last year, regional defence ministers had warned of long-term security problems lasting for decades if the unrest worsened or spread to neighbouring countries. The five-month battle ended in October last year, with the Filipino government declaring victory over the insurgents. By then, however, more than 1,000 were dead, and numerous homes destroyed.

A year on, Dr Ng told reporters on the sidelines of the 5th Asean Defence Ministers’ Meeting (ADMM) that the Marawi experience has prompted defence ministers from the 10 Association of South-east Asian Nations (Asean) and its eight partners to recognise intelligence sharing as the “single most important platform” in counter-terrorism.

“The devastation is very large given that there were only a few hundred (militant) troops,” Dr Ng said. “I think we all felt this must never happen again to any city within Asean.”

The Marawi battle began when government forces clashed with armed fighters from militant groups linked to the Islamic State of Iraq and Syria (Isis). The militants had burned a Catholic church, the city jail and two schools before occupying the main streets and major bridges of the city.

The fighting ended after two militant leaders were killed by government troops in a military assault.

The Filipino government has said the rebuilding of the city would take two to three years, and Dr Ng noted that the rebuilding costs would amount to around US$1 billion (S$1.3 billion).

Dr Ng spoke about Marawi as he touched on the issue of counter-terrorism, one of the three main thrusts of this year’s ADMM and ADMM-Plus meetings.

Earlier this year, six Asean member states — including Singapore, Malaysia and Indonesia — launched an intelligence pact aimed at improving regional counter-terrorism efforts.

Called Our Eyes Initiative, the countries involved will "explore ways to exchange strategic information on terrorism, radicalism and violent extremism", Singapore’s defence ministry said in January.

Under the initiative, senior defence officials will meet to exchange information on militant groups and develop a common database.

On Saturday, Dr Ng also touched on two other key topics at this year’s meetings: Chemical, biological and radioactive threats, as well as guidelines for unplanned air encounters which were adopted the previous day.

The Guidelines for Air Military Encounters (Game), which are not legally binding, aim to ensure safe separation between military aircraft over the high seas so as to avoid creating safety hazards, among other things. It is the first multilateral document in the world designed to reduce the risk of miscalculations and de-escalate tensions in the air.

“Whether land or sea, once a mishap occurs, there is a dynamic that ensues which you cannot control often,” Dr Ng said.

He noted that the ADMM-Plus members — which include Australia, the United States and China — have agreed to the guidelines “in principle” and are studying the adoption of these guidelines.

Dr Ng also responded to journalists’ questions about Asean’s role in United States-China relations, amid tensions between the two superpowers.

Beijing and Washington are locked in a trade war that has seen them impose increasingly severe rounds of tariffs on each other's imports.

Dr Ng said there were “small ways and large ways” in which Asean could play a role.

For instance, he noted that during the meetings, both the US and China were asked about the incident earlier this month where a US Navy warship had an “unsafe” interaction with a Chinese warship in the South China Sea.

“During our dialogue sessions, we didn’t hold back. We asked pointedly, what happened between the two ships, should we be worried? How are your relations?” Dr Ng said.

“Just the very act of Asean asking…I think, gives (US and China) pause to collect their thoughts, formulate strategies and place emphases,” he added.

He said he was “happy to hear” from both parties that stability and security are top most priorities.

On Saturday, the Republic handed over the chairmanship of the ADMM to Thailand.