The U.S. has not kept its promise regarding Syria's Manbij, Turkey will not allow the formation of a terror corridor south of its borders, Defense Minister Akar told U.S. Republican Senator Lindsey Graham.

Turkey and the U.S. had agreed to work on the withdrawal of the PKK's Syrian offshoot People's Protection Forces (YPG) from Manbij, a YPG-held region in northern Syria. The aim of the Manbij deal was to ensure security and stability in the province by eliminating YPG terrorists and ultimately handing the administration of the province to a body consisting of local people, but the U.S. has failed to do so.

The defense minister reportedly told Graham that YPG is part of the same group as the PKK, which is recognized as a terrorist organization by Turkey, the U.S. and the EU.

Furthermore, Akar highlighted Turkey's fight against all terrorist groups, including the PKK, YPG and Daesh.

Due to its links with the PKK, Ankara has called the YPG-held areas a "terror corridor" and said repeatedly it will not allow the region to turn into an autonomous region administered by the terrorist group.

Earlier on Dec. 19, U.S. President Donald Trump announced an immediate withdrawal of troops from Syria but later said that he did not have a specific time limit for the pullout, signaling to an extension of the presence of U.S. troops on the grounds.

Commanders of the U.S. Central Command (CENTCOM), who share close links with top YPG figures, have been reportedly resisting the withdrawal, asserting that Washington should not abandon the YPG, which is often portrayed as the sole power in the fight against Daesh.

Ankara has been infuriated by the U.S. support for the Syrian Democratic Forces (SDF), which is dominated by the YPG under the pretext of fighting against Daesh. The U.S. provided military training and supplied truckloads of weapons to the YPG, disregarding warnings from Ankara that the YPG is organically linked to the PKK, and partnering with one terrorist group to fight another was not acceptable.

Turkey says the weapons are ultimately transferred to the PKK – designated as a terror group by the U.S., Turkey and the EU – and used against Turkey. The PKK has been waging a terror campaign, which had led to the deaths of some 40,000 people, including women and children, since the 1980s.

The YPG's ultimate goal is to establish an autonomous region in northern Syria by connecting the northwestern Afrin canton to the Kobani and Jazeera cantons in the northeast. In response to the YPG threat near its borders, Turkey has launched two cross-border military operations along with Syrian moderate opposition groups in the past two years.