The lucky ones migrate outside the conflict zone—on harrowing journeys to refugee camps in Kenya or Yemen, or to Somaliland, the breakaway republic that once formed Somalia's northern swath.

Somali security forces said they killed several Islamic State fighters and seized eight jihadist outposts during ongoing military operations in the semi-autonomous Puntland region.

Somalia's information minister did not immediately respond to a request for comment. The group was officially recognised as the Somali province of Islamic State in 2017 and has been based in the ...