If Turkey encounters any stalling or misconduct by the US, Turkey could set up the zone by itself, the country's presidential spokesman said on Tuesday.
"We cannot confirm the information coming from the US side that the field is completely safe. We need to confirm it through our own sources," Ibrahim Kalin said, alluding to Turkish demands that the zone is rid of the PKK/YPG, a terrorist group the US has sometimes allied itself with.
On August 7, Turkish and US military officials agreed to set up a safe zone in northern Syria and develop a peace corridor to facilitate the movement of displaced Syrians who want to return home.
They also agreed to establish a joint operations center.
The agreement also envisaged setting up necessary security measures to address Turkey's security concerns, including clearing the zone of the terrorist YPG/PKK.
Turkey has complained of previous US stalling over the PKK/YPG leaving the northern Syrian town of Manbij.