The Pentagon, State Department and Congress have spelled it out loud and clear: Washington's Turkish ally has to choose. It can either have the S-400 Triumph missiles from Russia or the F-35 stealth fighters plus Patriot missiles from the US. If Ankara chooses to go ahead with the controversial Russian defence system, it will face “grave consequences”, US officials have warned. Predictably, Erdogan lashed out against US/NATO “double standards”, accusing them of trying to force him to withdraw from his deal with the Russians while keeping silent about the S-300s in the hands of other countries such as Greece, Bulgaria and Slovakia. Moreover, as a caution against overstepping “red lines,” he indicated that his government was contemplating purchasing the even more sophisticated S-500 model from Moscow. “Everyone knows that this issue has nothing to do with NATO, the F-35 project and the security of the US,” he said. “It is not about the S-400s,” but about Turkey “taking actions on its own accord.” He was speaking at the predominantly Kurdish southeast Anatolian city of Diyarbakir and referring to his envisioned actions in the predominantly Syrian Kurdish regions across the border. Erdogan's Defence Minister Hulusi Akar, chimed in from his Twitter account. Washington's threat to block delivery of the F-35s, which Turkey helps manufacture, defies the law and logic, he said. After all, Turkish pilots and technicians were already in the US, receiving training on how to operate this much coveted fifth generation multirole combat aircraft. Turkish accusations and arguments are unlikely to hold much water in the US where military experts strongly advise against delivering 100 F-35s that Turkey ordered if it goes through with the acquisition of the S-400 missile system and all quarters of government are of like mind on this matter. From Washington's perspective, the ball is now in the Turkish court. The S-400s versus F-35s squabble has been building up for several months but is only one aspect of a steadily souring bilateral relationship. “Turkish-US relations have never before experienced a situation of this sort,” said former Turkish ambassador to the US Faruk Logoglu in interview with the AhvalNews site's Gülten Sarı. “On top of the unresolvable, totally intractable problems that weigh upon this relationship, now the brand new and much more gravely consequential S-400 question has been added to the agenda of Turkish-US relations.” Moreover, Logoglu said, while this relationship has endured “very serious crises” in the past, the difference now is that “in addition to the accumulating bilateral regional problems, this time there have arisen different problems that can have serious consequences.” Prime examples are Erdogan's “crossing the line” in his support for Venezuelan President Nicolas Maduro, not to mention his increasingly closer relationship with Russian President Vladimir Putin. Officials in Washington are wary of the directions that Ankara is taking. Senator Thom Tillis, who is one of the group of senators who introduced a bill to block F-35 transfers to Turkey, said, “for many, many years, they (the leaders in Ankara) were moving in a direction that was more consistent with most of our NATO partners and now they're moving in a different direction.” Tillis added, “I believe that they've got to get on a positive path or it could spell difficulty for us.” The US Director of National Intelligence Dan Coats put it more bluntly in his annual threat assessment for 2019: “The growing authoritarianism of Turkey's leaders” has made Ankara “more willing to challenge US regional goals”. Perhaps payback time has already come in the form of news from the White House that the US now plans to leave some 1,000 troops in Syria, regardless of the pledge that Trump made in December to withdraw them all. Nothing could be more guaranteed to make Ankara see red as this, and can only mean that the US is still determined to support and protect its allies in northern Syria: the Syrian Democratic Forces (SDF) and its chief component the Kurdish People's Protection Units (YPG). If true, it will set the Turkish regime's designs for northern Syria back to square one. Meanwhile, in a curious but significant counterpoint to the controversy over the Turkish-Russian missile deal, First Lady Melania Trump undertook what turned out to be a controversial visit to an Oklahoma charter school that “was recognised with the 2018 National School of Character Award and was chosen because of its excellent academics and commitment to character education”, according to Stephanie Grisham, a spokesperson for the First Lady. Apparently, the school was founded by followers of the Muslim cleric Fethullah Gülen, Erdogan's erstwhile mentor and political ally turned enemy whom the Turkish government blames for the “attempted coup” in July 2018. The visit must have struck some form of terror in the heart of the self-appointed heir of the Ottoman throne, because suddenly he softened his tone: the divergence in points of view between Turkey and the US can be resolved in a manner consistent with their overlapping interests, Erdogan said. “This is the first conciliatory approach by Erdogan to Turkish-US relations and it may be a sign that the president's entourage sensed that there is a problem, and a serious one, that needs to be solved or pushed under the carpet at least until the Turkish local elections on 31 March,” wrote former Turkish foreign minister Yasar Yakis in Ahval last week. Still, Akar held the line for his boss, vowing that nothing was going to obstruct the delivery of the F-35s which are scheduled to arrive in Malatya in December, nine months from now. The S-400s are due to arrive about the same time. What does this mean? Professor Ümit Alperen of the Faculty of Economics and Administrative Sciences at Süleyman Demirel University believes that the uncertainty surrounding the S-400 deal will continue right up to the delivery date, regardless of how “satisfied” Ankara and Moscow are with the deal.