Captured battlefield cellphones, computers are helping the U.S. target and kill Islamic State’s leaders

U .S. military officers watched grainy video feeds at a small operations center in Baghdad on Tuesday as Predator drones tracked and killed three reputed Islamic State leaders — one after another — in the offensive on Mosul.

The targeted air strikes were due in large part to intelligence extracted from cellphones, computer hard drives, memory cards and hand-written ledgers recovered from battlefields and towns taken from Islamic State fighters.

Recently captured intelligence also has proved useful in providing clues to detecting potential terrorist plots, tracking foreign fighters and identifying Islamic State supporters around the globe, U.S. officials said.

The largest data trove was recovered when U.S.-backed Syrian rebel forces recaptured Manbij, an Islamic State stronghold in northern Syria, in mid-August. Intelligence agencies recovered more than 120,000 documents, nearly 1,200 devices and more than 20 terabytes of digital information, officials said.