Officials said that National Thowfeek Jamaath (NJT) was behind the attack, calling it a “small organization” that likely had international support. On Tuesday, April 23, officials said that Jammiyathul Millathu Ibrahim, another local group, was believed to be involved.
ISIS stepped in later on Tuesday and claimed it had orchestrated the attack.
In a statement released through its “news agency” Amaq, the group claimed, “The perpetrators of the attack ... were Islamic State fighters.”
“A security source told Amaq agency the perpetrators of the attack targeting the citizens of [US-led] coalition countries and Christians in Sri Lanka were Islamic State [ISIS] fighters,” it said.
Amaq later posted a picture of men the agency claimed were the suicide bombers and video footage showing seven men they said were the bombers pledging allegiance to the terror group.
ISIS seeks to impose Shariah law on an interpretation of the Quran and Muslim teachings and held parts of Syria, Iraq, and other countries in recent years before being beaten back by America and American allies. The group has inspired or carried out terror attacks around the world, including a mass shooting in Paris in November 2015, which left 137 dead, including seven terrorists, and an attack with a vehicle in New York City in October 2017 that left eight people dead.
Security experts agreed that the Sri Lankan attacks carried hallmarks of al-Qaeda, ISIS, and other international terror groups.
Phill Hynes, the lead terrorism expert at ISS Risk, a Hong Kong-based security consultancy, said that the attacks were focused on killing as many people as possible.
“These attacks were pure terrorism intended to extract maximum carnage,” Hynes said. “There had to be a significant degree of local support to mount an attack of this scale, probably 80 to 100 handling a range of operational tasks.”
Other experts also agreed with Sri Lankan officials that local groups likely had international support.
“With this scale of attacks, I don’t think this was only carried out by locals. There is most likely involvement of foreign groups or people, including people moving in and out of India or Pakistan,” said Labetubun.
Rohan Gunaratna, a Singapore-based security expert, said that NJT was the ISIS branch in Sri Lanka.
Perpetrators were known to have links to Sri Lankans who traveled to the Middle East to join the hard-line group in Syria and Iraq, he said.
Pratyush Rao, south Asia analyst at the Control Risks consultancy, said before ISIS claimed responsibility that there was no evidence linking it to the group.
“While the scale and sophistication of the attacks suggest an overseas link, there does not appear to be any evidence so far to link it directly to IS,” Rao said. “It is plausible though that the attacks may have been inspired by IS tactics and ideology.”