The White House has urged Turkey to exercise restraint after Turkish forces launched a military campaign in Syria's Afrin region. It warned that the campaign risked intensifying a humanitarian crisis and disrupting what had been a stable area. The U.S. Defense Secretary James Mattis has also said that the U.S. is "very alert" to the ongoing situation with Turkey. On Saturday, Turkey launched an operation dubbed "Operation Olive Branch". The incursion into the Afrin region targets the U.S.-backed Syrian-Kurdish Peoples' Protection Units.