Malaysian authorities announced this week the arrest of a group of 19 suspected Islamist militants who had plans to join the Islamic State in Syria, as well as carry out bombings on a brewery and bars in the outskirts of Kuala Lumpur.

The arrests took place between April and July, and seven of the suspects have already been brought up on terrorism charges. Several of the accused were apprehended at airports, where authorities said they intended to embark on flights to Turkey in order to join the extremist group, also known as ISIS and ISIL, which recently beheaded American journalist James Foley.

The news was the latest to underscore the increased influence the Middle Eastern conflict, and ISIS in particular, has exerted on small but well-connected extremist elements in Southeast Asia. Estimates vary widely, but Malaysian police believe at least 100 of its citizens could be fighting with the Islamic State.

Several hundred Indonesians and 150 Australians are also reported to have joined the group, along with a "handful" of Singaporean nationals, according to authorities. The Islamic State has seized on the support, recently releasing a recruitment video that features an Indonesian jihadist exhorting his compatriots to join him in Islamic State-controlled territory.

In May, a 26-year-old Malaysian factory worker named Ahmad Tarmimi Maliki reportedly blew himself up in Iraq, killing 25 Iraqi soldiers before members of the Islamic State stormed the military facility where they were based.

Malaysian and local authorities estimate at least 15 Malaysian nationals have already been killed in Syria.

Involvement in such a distant conflict is painful for many in Southeast Asia, the region with the most Muslims in the world. Historically, it has also been home to mainstream forms of Islam that are more syncretic compared to stricter interpretations in parts of the Arab world.

"It was far disconnected from the Middle East," Gregory Poling, a fellow at the Center for Strategic and International Studies who specializes in Southeast Asia, told VICE News. "Over the centuries there was a lot more mixing with traditional religions and Hinduism."

"You still have Muslims in Indonesia that can recite the Ramayana," he said, referring to the Hindu epic.

However, local piety began to change among some in the 1970s as Saudi evangelists, funded by the royal family's petrol dollars, decamped for the far reaches of the Muslim world to preach their conservative brand of Salafist Islam. In the 1980s, Indonesians and Malaysians joined the mujahideen in Afghanistan as they attempted, with American assistance, to expel Soviet forces. Just as al-Qaeda was birthed out of the CIA-abetted fight in Afghanistan, jihadist and al-Qaeda-linked groups in Southeast Asia can also trace their genesis to the return of fighters during those years.

The most prominent of those radical groups, Jemaah Islamiyah, wasn't officially created until the early 1990s. Its followers quickly spread throughout the region with intent to establish a pan-Southeast Asian caliphate spanning Malaysia, Singapore, Indonesia, Brunei, the Southern Philippines, and southern Thailand.

"Jemaah Islamiyah set up a number of cells that were responsible for certain functions — Indonesians did the fighting, while Malaysians raised the money and did most of the bomb making," Pek Koon Heng, Malaysia-born director of American University's ASEAN Studies Center, told VICE News.

In 2002, the group, coordinating with al-Qaeda, set off a series of bombs near in the resort city of Bali, killing over 200 — more than half of them Westerners tourists -- and thrust the region onto the radar of American counterterrorism officials.

After the Bali bombings, President Bush called Southeast Asia the "second front" in the US' global war on terror. Over the next decade, however, local authorities — with heavy US funding — were largely able to clamp down on Jeemah Islamiyah and other groups like Philippines-based Abu Sayyaf. Leaders were jailed, followers were forced underground, and remnants splintered.

But now, regional governments are once again concerned that returning fighters could restart radical groups or turn their wrath towards domestic targets. The alleged plans to target bars and a Carlsberg brewery in Malaysia's administrative capital, Putrajaya, indicate those attempts have already begun.

"We have to be prepared for when Indonesians come back from fighting in the Middle East," Sri Yunanto, an adviser to Indonesia's national counterterrorism agency said at a recent panel. "We have experience with Afghan fighters, Moro fighters (in the Philippines), we don't want ISIS alumni in Indonesia," he said.

The radicalization of disaffected members of the lower and middle classes in Southeast Asia is in many ways similar to what's occurred in European countries and Australia, says Poling. But it also comes as polls show the vast majority remain moderate, no different from populations in most countries in their views towards religion and politics. In Indonesia, surveys show that fighting terrorism is a high priority for most people.

"Perhaps they have folks coming from more conservative families, perhaps they grew up relatively disaffected, or went to conservative madrasas and ran into the wrong kind of people," said Poling.

The rise of Saudi-funded Wahhabist madrasas in the region has also coincided with greater persecution of members of minority Shia communities, a pattern that mimics increased sectarian strife in the Middle East. In March, more than 100 Malaysian Shias, including women and children, were arrested simply for attending a religious ceremony. Last December, Malaysian Home Minister Ahmad Zahid explained he had banned Shia books as they "derail from real Islamic teachings."

"We insist on Sunni as our main belief in Islamic teachings," Zahid said at the time.

Tensions are further ratcheted as Sunni Islam becomes a nationalistic totem and means to identify as a member of the country's Malay majority. By some accounts, more than 100,000 Iranians live in Malaysia, part of an estimated population of 250,000 Shia. Sixty percent of the country of 30 million is Muslim.

"The Malaysians have been cracking down on the Shia, and the Saudis of course are behind the anti-Shia campaign," said Heng. "Shia are increasingly being told that the form of Islam they are practicing is not real Islam."

Indonesia, while officially recognizing six religions including both Protestantism and Catholicism, only considers Islam as a singular entity, and this leaves some hardline groups to interpret that to mean nothing but Sunni Islam. Indonesia's one million Shias have felt the brunt of extremist ire.

In April, thousands attended a rally organized by the Anti-Shia Alliance, where Ahmad bin Zein al-Kaff, leader of the anti-Heresy Front, called for a jihad against all Shia. Without Islamists in power, he said "we will never be able to purge the Shiites."

For Malaysians, part of the current allure of the Islamic State is what they see "as defending Sunni Islam against Shia oppression," said a recent Center for Strategic and International Studies analysis.

Other minorities have been targeted, too. In June, mobs aligned with hardline groups and attacked a church in the Javanese town of Pangukan. It was the third church in Yogyakarta region to be attacked this year. Elsewhere, groups like the Islamic Defenders Front have busted up bars and protested beauty pageants they consider as affronts to Islam.

Returning jihadist can only serve to inflame sectarian tensions, says Heng.

"At what point do these jihadists start training their sites on non-Muslims at home?" she said. "If they decide to target them, all you need is a handful of militants to destroy the fragile equilibrium. This is true in Malaysia as well as Indonesia."

Radical sentiment, however, is still outside of the mainstream.

Indonesian president Susilo Bambang Yudhoyono this week called the Islamic State "embarrassing," and reiterated in an interview with The Australian that "Indonesia is not an Islamic state."

Meanwhile, the next governor of Jakarta province, Basuki Tjahaja Purnama, is not only Chinese but Christian as well. The man he is replacing, Indonesia's newly elected President Joko Widodo, is a fan of heavy metal music and prefers checkered shirts to traditional or religious garb.

But in a country as large and spread out as Indonesia, all it takes are a few to create havoc, says Heng.

"There's this big picture in the Middle East and what's happening in Southeast Asia is a reflection of that," she commented. "You're getting this second generation of jihadists, which is much more serious. I don't think it's going away anytime soon."