Australia's Foreign Minister Julie Bishop is known for making soberly and well-crafted statements. So when she warned in March that the so-called "Islamic State" (IS) terror outfit might declare an Islamic caliphate in the Philippines' Mindanao region, many listened attentively.

Speaking to Sky News, Bishop said the Australian government was concerned about IS fighters returning from the Middle East to their home countries in Southeast Asia, including the Philippines.

Bishop said that a local terrorist group, the Abu Sayyaf, had formed links with IS, which declared senior Abu Sayyaf leader Isnilon Hapilon an emir or leader in Mindanao. "This brings the threat right to our doorstep," she said.

Bishop's warnings seem to have been vindicated by the latest developments in the southern Philippines.

Marawi, a city of about 200,000 inhabitants, has seen fierce clashes between IS-allied Islamists and Philippine government troops for a week. Over a hundred people have reportedly been killed. The security forces have found it a daunting challenge to bring the situation under control.

Downplaying threats

The latest events in Mindanao would have frightened the government in Manila, says Felix Heiduk, a Southeast Asia expert at the German Institute for International and Security Affairs (SWP), a Berlin-based think tank.

"The army and the government until recently regarded the militants fighting there as local bandits who had never read the Koran but were just freeloading under the IS banner," Heiduk, who had just returned to Germany from the Philippines, told DW.

The threat posed by them had long been downplayed, partly because the government has managed to more or less advance peace talks with other more dominant Islamic groups in Mindanao like the Moro National Liberation Front (MNLF) and the Moro Islamic Liberation Front (MILF), the expert pointed out.

"Since the outbreak of the hostilities, the danger has been taken more seriously," he noted, citing President Rodrigo Duterte's decision to declare a state of emergency in the region.

A change in strategy

Over the past two years, there has been a clear change in the strategy of Islamic militant groups like the Maute or sections of the Abu Sayyaf, Heiduk underlined.

It can be witnessed not just in the rhetoric employed by these outfits, but also in their ideology and actions. "The groups that have sworn allegiance to IS have not engaged in kidnappings but rather operated more like traditional guerrillas. By engaging in attacks, bomb blasts and military conflicts, they want to challenge the state's authority and its monopoly on violence."

As early as in November 2016, about 300 fighters occupied the small town of Butig in Mindanao for four days and hoisted the black IS flag over the town hall. A similar approach can be seen in Marawi now.

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"If they are merely bandits who are interested in money, why would they seek to occupy a 200,000-strong city and face off a much larger military?" asked Heiduk. "This makes sense only if they are actually trying to conquer territory and build a parallel state structure there, just as IS has done in Syria and Iraq."

In this endeavor, the militant groups are helped by an increasing number of foreign jihadists. "A new feature is that the local groups are opening up to international fighters, and many Saudis, Yemenis, Indonesians, Malaysians and Singaporeans are among those now fighting under the IS flag, and among the extremists now killed in Marawi," said Heiduk.

Southeast Asia in the focus of IS

The groups are now led by Isnilon Hapilon. Hapilon is an Islamist preacher with a Philippine university degree. In the 1990s, he was active in the MNLF, a rebel group fighting for Mindanao's independence from the Philippines.

Later, he joined the Abu Sayyaf group and rose through its ranks to eventually become one of its leaders. For over ten years, Hapilon has been on the FBI list of the world's most wanted terrorists.

Among other things, he is accused of being responsible for the 2004 attack on a ferry in Manila Bay, in which 116 people died. The US has declared a $5 million bounty on his head. Following his swearing of allegiance to IS, the terror group named him an emir in southern Philippines.

That there are connections between IS and Hapilon's group is officially confirmed, but it's not clear how broad and deep these ties are, observers say.

International links

These links are not limited to Mindanao. They also extend to the Philippines' neighbors like Indonesia and Malaysia, which are increasingly threatened by IS supporters.

"I don't believe that the local Philippine groups are now expanding into neighboring countries," said SWP expert Heiduk, adding that it was more likely that IS-affiliated groups in Mindanao had attracted fighters from other countries by scoring gains on the ground.

"But it can be observed that due to Manila's crackdown, these fighters are returning to their countries, albeit even more radicalized and with a network that extends to Mindanao."

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Indonesia's government has already deployed troops in the northern part of the island of Sulawesi as it fears an infiltration of Indonesian fighters from Mindanao.

In Sulawesi, IS supporters have been active for some time. In the area around Poso, one of the most wanted terrorists in Indonesia, Santoso, has organized training camps for Islamist extremists for years. Malaysia's easternmost province, Sabah, is also increasingly considered a retreat.

These developments are likely to intensify in the coming months as the international community reinforces its fight against IS in Syria and Iraq. That imperils regional security even further.

With regard to the security situation in the Philippines, Heiduk says that radicalization is also driven by poverty, a lack of prospects and a civil war lasting 30 years. "As long as the core conflict in Mindanao is not resolved, IS will continue to gain ground there."