Turkish President Recep Tayyip Erdogan has warned that Turkey would "crush the heads" of Kurdish forces if they did not withdraw from a proposed safe zone along the border under a US-brokered deal.
If the pullout does not happen by Tuesday evening, "we will start where we left off and continue to crush the terrorists' heads," President Erdogan said in a televised speech in central Anatolian city of Kayseri.
Turkey has agreed to suspend its Syria offensive for five days and to end the assault if Kurdish-led forces withdraw from the proposed safe zone away from the border, after talks with US Vice President Mike Pence in Ankara.
President Erdogan also provided some details from his talks with the Americans, adding that Ankara agreed to the 120 hour time deadline after its initial demand of "one night" for the withdrawal.
"If the promises given to our country are not kept, as we did in the past we will not wait and restart the operation as soon as the time we have given ends," he said.
The Turkish leader said he also informed US President Donald Trump of Ankara's position during a phone call on Friday.
Mr Erdogan is due to meet with Russian President Vladimir Putin in the Black Sea resort of Sochi next Tuesday, which overlaps with the end of the 120 hour deadline.
Ankara considers Syrian Kurdish YPG militants to be an extension of the outlawed Kurdistan Workers' Party (PKK) -- a group that has fought a bloody insurgency inside Turkey for 35 years.
Meanwhile, the commander of Kurdish forces in Syria accused Turkey of sabotaging a US-brokered truce by blocking the withdrawal of his forces from a flashpoint border town in northeastern Syria.
In a wide-ranging interview with AFP, Mazloum Abdi, head of the Syrian Democratic Forces (SDF), said he still wished to see a role for the US in Syria to counterbalance Russian influence, while recommitting his forces to countering the Islamic State group.
"The Turks are preventing the withdrawal from the Ras al-Ain area, preventing the exit of our forces, the wounded and civilians," Abdi said in a phone interview from Syria.
Mr Abdi said he could not abandon his forces in the town, which is besieged by Turkish troops and their Syrian allies.
Earlier, Turkey accused Kurdish forces of violating the ceasefire agreement.
"The Turkish armed forces fully abide by the agreement" reached on Thursday with the United States, the defence ministry said in a statement. "Despite this, terrorists... carried out a total of 14 attacks in the last 36 hours."
The ministry said 12 of the attacks came from Ras al-Ain in northeastern Syria, one from Tal Abyad and another from Tal Tamr region, adding that various light and heavy weaponry including rockets were used.
The defence ministry said "for the agreement to hold soundly and to keep the calm with exception of self-defence", Turkey was coordinating with the United States.