Turkish President Recep Tayyip Erdogan said on Friday that if the United States does not keep its promises after Turkey stops its military operation in northern Syria for 120 hours, Ankara will then continue its offensive.

In case the promises are not kept, the Turkish offensive will resume "the minute the 120th hour ends," Erdogan told the foreign press in Istanbul.

Ankara and Washington agreed on a 120-hour truce on Thursday for the withdrawal of the Kurdish militia from the safe zone to be established by Turkey in northern Syria following a visit by U.S. Vice President Mike Pence.

Erdogan noted that the region between the Syrian towns of Tal Abyad and Ras al-Ayn was cleared of the Kurdish militia known as the People's Protection Units (YPG).

"The process has been continuing," he added, noting that there are Russian soldiers in Qamishli and Syrian government forces in different places.

He said he would discuss these areas with his Russian counterpart Vladimir Putin when they meet on Oct. 22 in the Russian city of Sochi.

The Turkish leader vowed to respond if the Syrian government "makes a mistake" in the region.

Turkey plans to establish 12 observation posts in the safe zone so as to shelter up to two million Syrian refugees, he said.

Turkey is hosting some 3.6 million Syrian refugees on its land, a huge burden for the country beset by an ailing economy.

Turkey launched a military offensive on Oct. 9 to clear the Kurdish militia from northeastern Syria for a safe zone, as Ankara sees the YPG as a terror group.