 Beginning in March 1991, the U.S. and some of the Gulf War allies barred Saddam's forces from conducting jet aircraft attacks by establishing the no-fly zone over northern Iraq and provided humanitarian assistance to the Kurds.On April 17, U.S. forces began to take control of areas more than 60 miles into Iraq to build camps for Kurdish refugees; the last American soldiers left northern Iraq on July 15.In the Yeşilova incident in April, British and Turkish forces confronted each other over the treatment of Kurdish refugees in Turkey.