A U.S. raid mistakenly killed a Syrian undercover agent, complicating ties amid efforts to combat the Islamic State.

A U.S. raid mistakenly killed a Syrian undercover agent, complicating ties amid efforts to combat the Islamic State.

DUMAYR, Syria: A raid by US forces and a local Syrian group aiming to capture an Daesh (IS) group official instead killed a man who had been working undercover gathering…