Still later on Tuesday, Amaq published a video showing eight men — apparently the Sri Lanka attackers — pledging allegiance to Abu Bakr al-Baghdadi, the leader of ISIS, whom they called “emir of the believers.” They held their hands up, index fingers pointed skyward, in a gesture that the Islamic State has adopted to refer to belief in one God.

The men are masked, except one who appears to be Mohammed Zaharan, who has been identified by Sri Lankan officials as the leader of the group that carried out the bombings.

A day earlier, an ISIS-linked chat room on the app Telegram had posted photos of masked men it identified as “commandos” involved in the bombings. It used three noms de guerre that match three of the names used in the militants’ statement.

If it is authentic, the video indicates that the cell in Sri Lanka took steps to ensure that its violence would seen as being committed on behalf of ISIS, which has repeatedly called for assaults on churches, particularly since the New Zealand mosque attacks.

It does not necessarily mean there was direct communication or guidance from the terrorist group, but it indicates that the assailants were steeped in its ideology, and familiar with the terminology and rituals of carrying out an attack in ISIS’ name.

If true, the claim of Islamic State responsibility also demonstrates that the group still poses a threat, despite the loss of the territory it once held in Syria and Iraq.

The attackers got help while overseas, and some were in Syria

“There seems to have been foreign involvement” in the bombings, Prime Minister Ranil Wickremesinghe said at a news conference. Investigators believe, he said, that some of the attackers “have traveled abroad and have come back.”