Despite Ankara's clear discomfort, Washington is reportedly determined to establish observation posts along the Turkish-Syrian border in regions controlled by the PKK-affiliated groups.

U.S. Defense Secretary Jim Mattis announced last week that they will set up observation points in several locations along the northern Syrian border to address Turkey's legitimate security concerns over the U.S.' support for the PKK-affiliate People's Protection Units (YPG).

Nevertheless, the U.S. reportedly will task YPG terrorists in the observation posts along with the U.S. Central Command (CENTCOM) troops. A high ranking official from the YPG told the London-based Asharq Al-Awsat on Saturday that the U.S. is setting up observation points with an aim to protect the YPG from a likely Turkish operation east of the Euphrates River, which Turkish officials have been signaling for some time now.

"The U.S. Army started yesterday [Friday] establishing three posts in Tal Abyad and two others in Ain al-Arab at the border with Turkey to protect its Syrian ally forces against [Daesh]," the source added and underscored that YPG terrorists will be deployed to these observation points.

U.S. support for the terrorist organization has long vexed Ankara as Washington views the YPG as a reliable partner in its fight against Daesh and continues to provide it with arms and equipment. Turkey has repeatedly said that YPG is no different from the PKK, which has been fighting against Turkish states for 40 years and claimed more than 40,000 lives. Yet, Washington denies the PKK's connection with the YPG.

Ankara also conveyed its discomfort to the U.S. over the establishment of observation points in Syria. Many regarded Washington's recent moves as an attempt to distinguish and legitimize the YPG's existence in Syria.

Defense Minister Hulusi Akar said on Saturday he told U.S. Chief of Staff Joseph Dunford and other U.S. officials during a recent visit to Canada on the sidelines of the Halifax International Security Forum last Sunday that setting up the posts would have a very negative impact on perceptions of the United States in Turkey.

"We have stated that the observation points to be established by U.S. troops on the Syrian border will have a very negative impact... and in the course of our discussions we expressed that it could lead to a perception that ‘U.S. soldiers are somehow protecting terrorist YPG members and shielding them,'" he added.

In relation to the issue, Can Acun, a Syria expert, recently told Daily Sabah that latest moves of the U.S. including putting $12 million bounties on three key PKK leaders and establishment of observation points under the pretext of addressing Turkey's security concerns over YPG may be in fact an attempt to prevent a Turkish military operation.

The source also revealed a secret one-year memorandum of understanding signed with the U.S.-led coalition to train 30,000 YPG militants in addition to the already existing 60,000 forces.

In February, Washington announced its plans to form a 30,000-strong border security force in northern Syria with the YPG, which drew harsh reactions from Ankara, but later declared that the force would only secure the border between Jordan and Lebanon instead of the Iraq-Syria border.