Turkey has increased its forces on the northern border with Syria prior to operation against US-sponsored militants in the region.

The number of Turkish military patrols on the frontier with armored vehicles “increased” in the border town of Akcakale, across from Tal Abyad in Syria, the private DHA news agency reported on Sunday.

The Turkish state-run Anadolu news agency had earlier said that at least nine trucks carrying armored vehicles and a bus with military personnel on board had reached Akcakale in Sanliurfa Province late on Saturday.  

President Recep Tayyip Erdogan on Saturday renewed his pledge to start an “air and ground” offensive against the militants of the so-called People’s Protection Units (YPG).

“We have made our preparations, completed our operation plans,” Erdogan said at a meeting of the ruling AK Party in Kizilcahamam in Ankara Province. “We have given the necessary orders.”

The US has long been providing the YPG with arms, calling them a key partner in the purported fight against the terrorist group of Daesh. Many observers, however, see the support as part Washington's plans to carve out a foothold in the Arab country.

That support has also angered Washington’s NATO ally Turkey, which views the YPG as a terrorist organization tied to the homegrown Kurdistan Workers’ Party (PKK). The PKK has been waging a war inside Turkey for decades.

On August 7, Turkey and the US reached an agreement on the establishment of a joint operation center in northern Syria after Ankara threatened to launch an operation against YPG militants and push them away from the Turkish border.

Turkey seeks to establish a 32-kilometer “safe zone” in northern Syria, and has stressed that it wants the YPG cleared from the region.

Neither Turkey nor the US has authorization from the Syrian government for their activities in Syria.

Turkish Foreign Minister Mevlut Cavusoglu recently voiced doubts whether joints efforts with the US to form the so-called safe zone in northeast Syria would ever produce the expected results.

The Syrian government has slammed the agreement, condemning it as a violation of Syria’s sovereignty and territorial integrity as well as international law.