"We will launching off to Ankara in the next 24 hours," the official said, a day after Pence announced his trip to Turkey without specifying the timing.
Turkey on Tuesday vowed to pursue its Syria offensive and slammed a "dirty deal" between President Bashar al-Assad's regime and Kurdish forces after the withdrawal of US forces from northern Syria.
"We will continue to combat all terrorist groups, including Daesh, whether or not the world agrees to support our efforts," Fahrettin Altun, communications director at the Turkish presidency, told AFP, using an alternative acronym for the Islamic State group.
Turkish presidency slams 'dirty deal' between Syria's Assad and Kurdish forces.
The United States is not aware of any "major" escape of Islamic State extremists.