As Libyas stability continued to deteriorate, at least three militant groups, one in each of Libyas three regions, pledged allegiance to ISIS. In February 2015, a group of the militants aligned with ISIS beheaded 21 Egyptian Coptic Christians who had been kidnapped from Sirte. Egypt responded by launching airstrikes on weapons depots in Derna, a militant stronghold in eastern Libya. In May, ISIS militants shot or beheaded at least 20 Ethiopian migrant workers, most of whom are believed to be Christian.