The creation of a new military force in Syria raises fears of fighting among American allies and could draw the U.S. deeper into the conflict.
After phone calls with world leaders and a golf outing with Tiger Woods, the president had time to revisit a favorite grievance: the selection of person of the year.
As the diplomatic dispute lingers, Turks and Americans are struggling with the effects, and the United States is demanding protection for its consular staff.
The Turkish government has dismissed telephone recordings as fabrications concocted by treasonous adversaries. But United States prosecutors have taken a different view.
Investigators have also questioned witnesses about whether Michael T. Flynn was secretly paid by the Turkish government in the final months of the 2016 presidential campaign.
The authorities announced that they had charged 12 Turkish security personnel and four other American and Canadian civilians in connection with an attack on protesters.