WASHINGTON (Reuters) - U.S. President Donald Trump will speak by phone soon with Turkish President Tayyip Erdogan to raise U.S. concerns about Turkey's offensive against Kurdish forces in northwest Syria, a senior administration official said on Tuesday.

The official, who briefed reporters on condition of anonymity, said Turkish officials have sent "conflicting signals" about the scope and duration of the offensive against the U.S.-backed Kurdish YPG in Syria’s Afrin region.