A helicopter accident in northeastern Syria over the weekend left 22 American service members injured, the U.S. military said Tuesday, adding that the cause was under investigation and no enemy fire was involved. The military statement said the service members were receiving treatment and 10 were moved to “higher care facilities” outside the region. Pentagon spokeswoman Sabrina Singh said at a media briefing that the mishap involved a single MH-47 Chinook helicopter. The Chinook “had a problem with one rotor that caused a hard landing during takeoff,” Singh said. All of the service members involved in the crash were in...