WASHINGTON — Bilal al-Sudani was no stranger to American counterterrorism officials.
Before joining the Islamic State affiliate in Somalia, Mr. al-Sudani was subjected to punitive sanctions by the U.S. Treasury Department in 2012 for his involvement with Al Shabab, Al Qaeda’s branch in the East African country.
But it wasn’t until American officials started digging deeper into the background of another Islamic State branch, the one in…
