Ankara said that it is not distancing itself from the NATO alliance by buying the Russian S-400 missile defense systems, underlining that Turkey abides by all of its commitments and has fulfilled all of the obligations under the joint program for the F-35 fighter jet. "In this program, there is no such clause saying that one will be removed from the program if it buys the S-400. Removing us from the program upon the request of any of the program members will be contrary to law and justice," Defense Minister Hulusi Akar told NTV yesterday, reiterating that the S-400 and F-35 systems will not affect each other.

He said Turkey was trying to explain to the United States and other partners in the F-35 project that the S-400s would not pose a threat to the jets, and added that Ankara had taken measures to prevent that.

In his strongest challenge yet to warnings that Turkey may be removed from the F-35 project, President Recep Tayyip Erdoğan said on Tuesday that the project would collapse if Turkey did not participate.

While Washington has warned of potential U.S. sanctions if Ankara pushed on with the S-400 agreement, Turkey has said it would not back down from the deal.

Instead, Turkey has proposed to form a working group with the United States to assess the impact of the S-400s, but says it has not yet received a response from U.S. officials.

Foreign Minister Mevlüt Çavuşoğlu also said yesterday that relations between Ankara and Washington do not hinge on the S-400 or F-35 deal. "We urgently need defense systems. For 10 years, we have been trying to acquire them from our NATO allies, but they did not sell them so far," Çavuşoğlu told reporters after a press meeting with his Hungarian counterpart Péter Szijjártó.

Similar to Akar, Çavuşoğlu refuted claims that the S-400s would pose a threat to the F-35 jets.

Speaking on the U.S. support to PKK-affiliated People's Protection Units (YPG), Akar underlined that Turkey may be forced to take unilateral actions in the northern Syria if the U.S. and Turkey failed to reach an agreement over the YPG presence along its border as it did in its two cross-border operations in the last two years.

"We should reach a mutual decision and determine measures on [the safe zone] as soon as possible. We previously worked together but when it was not possible, we unilaterally launched Operation Euphrates Shield. We already conveyed to them that we do not want to find ourselves in such situation again," Akar said, referring to U.S. Special Envoy for Syria James Jeffrey's meetings with Turkish officials on the planned safe zone along the Turkish-Syrian border.

Noting that they have voiced their demands and recommendations as regards to the safe zone very clearly, Akar stressed that Ankara will never accept the presence of a terrorist organization near its border and will take every measure they can.

Turkey had long signaled a possible operation in areas held by the YPG east of the Euphrates. However, the government decided to postpone the operation for a while after U.S. President Donald Trump decided that Washington, the main backer of the terrorist group, would withdraw its troops from Syria.

The withdrawal decision was quickly interpreted as an intention to halt U.S. support for the YPG, which Turkey sees as a terrorist organization. Yet, in the face of mounting hints that the country will maintain its support to the terrorist organization and contradicting statements from officials on the pullout process, Erdoğan and Trump began to discuss setting up a 32-km deep safe zone to ease Turkey's security concerns.

In relation to the issue, Akar underscored that Turkey will not make any concession on the administration of the safe zone, which should be under Turkey's control, adding that they also demanded the safe zone to have at least 30-40 km deep extending southwards.

Regarding to Turkey's efforts in Syria, President Recep Tayyip Erdoğan said on Friday that Ankara could not receive necessary support from international community to provide security for Syrian refugees returning their countries. He added that some powers are planning on a "Turkish spring" over last local election results, which won't be allowed.

Pointing out that YPG also has been using explosive-laden drones as a strategy for the areas that they cannot reach, Akar underscored that the retrieval of all the weapons provided to the terrorist organization was necessary to ensure the full elimination of security concerns.

He underscored that although there was positive feedback in the meeting, the U.S. has been showing flexibility from the start and they have been losing time on the matter.

Meanwhile, RaeJean Stokes, U.S. Embassy spokesperson, emphasized that the talks between Jeffrey and Turkish officials on Syria were positive and constructive. "We continue to make progress in addressing our mutual concerns in Syria, and we look forward to continuing these discussions in the near future," Stokes said.

She noted that the discussions focused on how both countries could advance issues of mutual concern areas in Syria, to include addressing Turkey's legitimate security concerns, promoting stability and security in northern Syria as the U.S. military draws down its presence, adding that the implementation of UNSCR 2254, which was unanimously adopted in 2015 urging a cease-fire and political settlement, were among other agenda items discussed in the meeting.

Ankara-Washington relations have been at odds for some time now due to the latter's support for the terrorist organization as Turkey argued that using one terrorist to fight another is illogical. Turkey sees the YPG as an extension of the PKK, which has claimed the lives of more than 40,000 people in a 30-year terror campaign. The U.S., however, while listing the PKK as a terrorist group, opted to continue its militarily support for the terrorist organization, by providing truckloads of military supplies and military training under the pretext of fighting Daesh, despite the warnings of its NATO ally.