The deadly Paris-style attack in Jakarta has thrown a spotlight on a shadowy Southeast Asian faction of ISIS group and offers new evidence of the spread of ISIS franchises.
Under growing pressure in Iraq and Syria from the US-led bombing campaign, the extremist group is spreading its tentacles, metastasising into new regions.
The IS group already has affiliates in Libya and Nigeria, and has targeted a host of other countries like Yemen, Somalia and Afghanistan, using its signature brutality to lure disaffected fighters from other jihadists like the Taliban.
Now, with its claim of responsibility for Thursday's suicide bomb and gun attacks in Jakarta -- which left five attackers and two other people dead -- the brutal grouping appears to be getting a foothold in Southeast Asia.
"IS is changing strategy," said Jakarta police chief Tito Karnavian, the former head of Indonesia's anti-terrorism unit.
"They are establishing branches of IS across the world -- in France, Europe, Africa, Turkey as well as Southeast Asia," he told reporters this week.
Indonesian police have pointed the finger at Katibah Nusantara, a militant unit of Malay-speaking ISIS jihadists fighting in Syria.
While there has as yet been no direct Katibah Nusantara claim, the group has loomed ever larger on the radar of ISIS-linked groups.
Its extended name translates roughly as "Malay Archipelago Unit for the Islamic State in Iraq and Syria."
Its goal: a Southeast Asian outpost for its global caliphate.
The faction's fighters, primarily from Indonesia and Malaysia and who coalesced along shared lines of language and culture, rose to prominence in 2015 after distinguishing themselves on the battlefields of Syria and Iraq, helping to capture territory.
Those victories were a Southeast Asian publicity coup for IS, which trumpeted them in glowing terms on social media in the Malay language, publicity aimed squarely at potential jihadists across the region.
Police say Katibah Nusantara is led by Bahrun Naim, who they accuse of orchestrating Thursday's attacks from Syria, where he is believed to be instructing Southeast Asian militants and organising recruitment.
He has been described in some media reports as a former Internet cafe employee.
Analysts say he was previously imprisoned briefly in Indonesia on suspicion of terrorism involvement, and has been linked with other extremist groups in the past.
"He is an active player," said Joseph Chinyong Liow, an expert on Southeast Asian Islam at Singapore's S. Rajaratnam School of International Studies.
"He has a website which celebrates IS and its successes, and more specifically, he celebrated the Paris attacks."
Sidney Jones, a regional terrorism expert, has called him an "ex-prisoner and jihadi intellectual", saying he was involved in a previous plot last year to carry out an attack in Indonesia, which appears not to have gone ahead.
Indonesia suffered several large and deadly bomb attacks by Islamic radicals between 2000 and 2009, but a subsequent security crackdown weakened extremist networks, and there had been no major attacks for years.
If Katibah is responsible, the Jakarta violence marks its first high-profile strike in its home region, and will challenge Indonesian authorities to once again tame the extremists in their backyard.
"One of the saving graces for Indonesia over the last five years is that local terrorists have thought small," Jones wrote in a recent analysis of Katibah Nusantara.
"Bahrun Naim and some of his friends think bigger."
Some fighters from Southeast Asia have returned from the Middle East with tales of disappointment at being given little respect or responsibility there, analysts said.
But the language and cultural commonalities of Katibah Nusantara followers could help keep fighters in the fold and provide an enduring tool for coordinating attacks across Southeast Asia and recruiting more fighters to Syria, analysts said.
ISIS group "is very sophisticated and professional in their militancy, in every sense of the word", said Liow.
"It does appear to be able to capture and captivate the imagination of many Muslims in this part of the world."