A deadly bombing of a cathedral in the Philippines has brought fresh attention to the Islamic State’s ability to metastasize across the world, even as the militant group has been reduced to a sliver of turf in Syria.

The attack, consisting of two detonations, struck the Cathedral of Our Lady of Mount Carmel on the island of Jolo at the southern end of the Philippines, a region where Muslim insurgents have for decades battled the Catholic-majority state. At least 20 people were confirmed dead in the assault, which took place just as worshipers gathered for Mass on Sunday.

Through various online bulletins, the Islamic State, also known as ISIS, claimed responsibility.

Read more: New York Times