The Turkish military is preparing for a military operation to seal its Syrian border from the presence of the Democratic Union Party's (PYD) People's Protection Units (YPG) terrorists. The city of Afrin, which is in northwestern Syria, is a priority area for Ankara to prevent the emergence of a de facto political-military entity controlled by the PYD on its southern border. The YPG's increased presence along the Turkish border is becoming a fundamental national security challenge for Ankara. As declared after the last National Security Council (MGK) meeting, Turkey is determined to contain terrorist elements along its borders and will not refrain from cross-border military operations to this end. Ankara's efforts to contain the YPG threat on its border is not limited to Afrin, and most probably will extend to the eastern parts of Turkey's border with Syria, as well. However, the Pentagon is simultaneously increasing its military buildup in PYD-controlled areas of Syria. The Pentagon has not tried to hide its objectives to create a border force of 30,000 troops in northern Syria predominantly composed of YPG militants. Interestingly, Turkey's border with Syria is at the same time NATO's border with Syria, but the Pentagon rather prefers to arm, equip and train terrorist elements that target NATO ally Turkey. Washington's continuous support for the YPG is creating constant outrage among Turkish officials. U.S. President Donald Trump's earlier promise to President Recep Tayyip Erdoğan to discontinue arming the YPG and collecting the weapons it delivered to the Syrian Democratic Forces (SDF) to fight against Daesh after the Raqqa operation was not fulfilled. On the contrary, the Pentagon increased its arms deliveries to the forces in PYD-controlled areas. Either Trump did not tell the truth to Turkish authorities or he is not able to decide key national security issues by himself. No matter what is behind America's decision not to keep Trump's promises to Turkey, Ankara does not hide its frustrations anymore. Turkish-U.S. relations are facing their lowest point since Turkey became a NATO member in 1952, and it seems that things will only get worse if Washington continues to support terrorist elements that threaten Turkey's security. Most people in Turkey perceive that Washington is trying to contain Turkey by using YPG and Gülenist Terror Group (FETÖ) elements. Washington's unfriendly steps and efforts to mislead Turkish authorities with regard to the YPG is helping to strengthen this perception. In a speech at the Hoover Institution on Jan. 17, U.S. Secretary of State Rex Tillerson said that the U.S. will continue to maintain its presence in Syria to protect U.S. security interests. He also mentioned the fight against Daesh and al-Qaida and limiting Iran and Hezbollah's influence in Syria as the main objectives of the U.S. presence in Syria. Tillerson added that the U.S. takes Turkey's concerns about the YPG seriously, yet American authorities have done nothing to overcome those concerns. It seems that the Pentagon has long-term plans in Syria, as Tillerson also mentioned rebuilding Syria to prevent hostile elements that may threaten U.S. interests from filling the power vacuum. What disturbs Ankara is Washington's choice of partner in its efforts to redesign northeastern Syria. Turkish authorities are concerned because Washington has never been transparent or honest about its collaboration with YPG forces. It seems that the U.S.-YPG collaboration is turning into a strategic alliance. Ankara believes that Turkey may be one of the targets of this alliance since the Daesh threat is already diminished. Washington has its own frustrations related to Ankara over the past decade, especially since the U.S. occupation of Iraq in 2003. Turkey was not willing to play the Middle East game along with the U.S. The Pentagon's skepticism about Turkey surged after Parliament denied access to air bases in Turkey for the American invasion of Iraq. However, Washington and Ankara continue their strategic collaboration in many other key security issues. Washington's current alliance with the YPG is shortsighted because it will thwart strategic cooperation between Turkey and the U.S. and could also initiate a proxy military confrontation between the two countries over PYD control of northern Syria. This could destabilize Turkey's security as well as damage the U.S.'s broader strategic interests in some other parts of the region surrounding Turkey. In recent months, Washington has been playing a risky game with NATO ally Turkey. One of the reasons behind this risky policy is Washington's underestimation of Turkey's defense capacity and political will, especially after the failed coup attempt on July 15, 2016. Washington constantly underestimates the Turkish security apparatus's capacity and willingness to fight against terrorism and political will. Some analysts at the Pentagon most probably make assessments with information provided by fugitive FETÖ members who served in the Turkish military before the failed coup attempt. For those assessments, it is a golden opportunity and the right time for Washington to bypass Turkey in its efforts to design northern Syria. Another reason behind this risky policy against Turkey is the Pentagon's misjudgment about the PYD and YPG's capacity. The Pentagon is miscalculating the PYD's potential and capacity in Syria. The PYD's YPG militia would not be a powerful actor in Syria if the Pentagon had not supported and armed it against Daesh over the past two years. They try to use the SDF title, but the SDF is dominated by YPG forces. The PYD does not represent the Arabs in Syria, and it also does not have close ties with moderate Kurds who want to have friendlier relations with Turkey and their Arab neighbors. The Pentagon uses the PYD and YPG's desire for territorial control and political status for its own goals. These reckless moves may damage the long-term interests of Kurds in the region and lead to further marginalization of Kurds. The PYD could turn into a liability for both Washington and millions of Kurds in the region. Washington's risky game with the YPG and Turkey's severe military response to this organization has a potential to bring the strategic cooperation between these two countries to the brink of collapse. Tillerson's recent statements about Washington's Syria policy and the Pentagon's efforts on the field falls short of convincing Turkish authorities to change their plan of action against the YPG. Turkish-American tension may also lead to severe damage to the NATO alliance. [Daily Sabah, 18 January 2018]