US president Donald Trump’s relationship with Recep Tayyip Erdogan, his Turkish opposite number is a curious one. Trump, along with most legislators in Washington were incensed when Erdogan pressed ahead with the purchase of the Russian S-400 antiaircraft missile system, in defiance of US pressure and at complete variance with Turkey’s obligations to the US-led NATO alliance of which it is a member.

Washington hit back by dropping Turkey from its F-35 fighter production program on the very obvious grounds that allowing Turkish plane makers to produce parts of this new advanced fighter was an absurdity in terms of security, given Ankara’s new close defense relations with Moscow. Turkey had been due to buy 100 of these new US warplanes but the complete fulfillment of the order is now in doubt.

Though Trump huffed and puffed about Erdogan’s Russian arms deal, it did not appear to undermine the admiration he had expressed in the past for the Turkish leader. At the very least, both men share a bluntness, a certain lack of subtlety. But then came Trump’s precipitous decision, to the dismay of his military and diplomatic advisers to pull US troops out of the campaign in northern Syria where, in alliance with local Kurdish forces, a great deal to destroy the remaining elements of Daesh (the so-called IS). This decision caused widespread shock because it meant leaving the Kurdish region at the mercy of the advancing Turkish army. Yet, even as American forces were withdrawing, Kurdish YPG fighters were instrumental in the tracking down and death of the terrorist leader Abu Bakr Al-Baghdadi.

In typical Trump fashion, there was no open admission that his withdrawal decision had been a mistake, though it seems certain that the ramification of his move did dawn on him later. Some of the US troops only away from likely contact with advancing Turkish troops. Meanwhile Trump wrote to Erdogan pressing him not to cause bloodshed but recommending that he seek to achieve his ends through negotiation. He warned that if Turkey refused, he would trash the country’s already struggling economy.

It is hardly surprising that Erdogan considered this letter ridiculous. Ankara insists that the YPG is directly linked to Turkey’s own Kurdish rebels, the PKK, which it and much of the international community consider a terrorist organization. An aide said the Turkish president had tossed Trump’s missive into the trash can. It might have been expected that the tensions between the two leaders might led to the cancellation on Erdogan’s visit to Washington. But the Turkish leader duly arrived at the White House this week to be greeted warmly Trump. He was ungenerous in his response. He handed Trump’s letter back to him and told him to his face not to be “a fool” and try to play the “tough guy”. Remarkably at their post-meet press conference, Trump was still smiling.

It must therefore be wondered what else is going on here. If the US President is prepared to swallow insults from his Turkish counterpart, he has to have a reason. But given Erdogan’s Russian missile purchases, his assault of Washington’s erstwhile Syrian Kurd allies and his consistent rudeness towards the White House, it is very hard to see what that reason is.