Learning from past experiences with the growth of radicalism, the Indonesian government is bolstering security along its frontiers.

The Defence Ministry, the National Counterterrorism Agency ( BNPT ), the intelligence services, the military, and National Police will co-ordinate efforts to secure the country's borders against the jihadist threat, according to Defence Minister Purnomo Yusgiantoro.

"The border between Indonesia and Malaysia and also the border between the southern Philippines and Sulawesi are important. These are places where radicals can cross the border using false identities. Militants can come for preaching, recruitment, and maybe also to transfer weapons," he told Khabar Southeast Asia.

Securing the border not only will prevent militants from crossing into Indonesia, but also prevent home-grown militants from fleeing to neighbouring countries, Purnomo said.

"Since ISIS [Islamic State of Iraq and Syria] followers have declared their desire to build a caliphate in the Southeast Asian region, increased border security is essential," BNPT chief Ansyaad Mbai told Khabar.

In the past, al-Qaida-linked militants crossed into Indonesia from Malaysia and the Philippines – and vice versa – taking advantage of weaknesses in border security, he said.

"Militants and ISIS followers have bigger dreams in uniting all Muslims under the caliphate," Ansyaad added. "They are clearly pursuing the ideas of unity."

The counterterrorism chief again emphasised the importance of anticipating threats of violence after Indonesian jihadists come back from the Mid-East.

"Those efforts will include how to disengage them after they return home," he said. "It is a big task for us."

General Moeldoko , armed forces commander, said that securing the borders was essential to countering ISIS's international spread.

"We are taking this situation seriously and will continue to be vigilant. We have learned from our past experiences, and we will not underestimate the importance of border security," the general told Khabar, adding that returning jihadists could also pose a wider threat in Southeast Asia.

"We are also focusing on foreigners travelling in Indonesia – especially those who have links with radicalism and militant groups," Moeldoko said.

However, the borders cannot be secured without help from communities that straddle them, Jakarta cleric Muhammad Muchalis Wisnu pointed out.

"I think this good effort must be followed and supported by a commitment among communities at the borderlines," Muchalis, 45, told Khabar.

"It is crucial to educate people at the borders that ISIS's ideology is not in accordance with Islam and that Muslims should fight against them to prevent the spread of ISIS's ideology."