Can the US really act against ally Turkey for buying Russian system?

Presidents of the United States always love giving ultimatums in order to get their way. Donald Trump is no exception. Trump has been warning Turkey's President Erdogan for months not to buy the Russian SS-400 air-defence system. As a Nato ally, and an important one for the alliance, Turkey is supposed to buy what it needs to defend its country from friendly, preferably fellow alliance nations. Partly because it's the Nato thing to do and partly because of the importance of having weapon systems that are interoperable within the alliance. But Erdogan is also friendly with Vladimir Putin and, understandably, he liked the look of the Russian SS-400 air-defence system. It's probably the best of its type in the world. The Russians are already well into having the next-generation system, called SS-500. So Erdogan decided he wanted the best and chose the Russian SS-400. The US went ballistic and said he couldn't and shouldn't do this and threatened to stop Turkey buying the American F-35 Lightning II superfighter. Erdogan took a gamble and went ahead with buying the Russian system and now the first parts have arrived. In other words, Erdogan is ignoring Trump's warnings and ultimatums and doing what he wants. So will the US throw Turkey out of the huge F-35 programme? The programme for Turkey is already suspended by Congress. But to expel Turkey altogether would be a major deal. This is a key Nato member. Also the US needs all the Nato countries and other allies it can get into the F-35 programme to make the whole vastly expensive project more affordable. There's a tricky problem here. If the US accepts the inevitable, allows Turkey not just to go ahead with deploying the SS-400 system but also to buy 100 or so F-35s, then the Russians could hugely benefit by discovering, through their air-defence system in Turkish hands, how vulnerable the F-35 is to its air-defence technology. Erdogan has it in his head that Trump doesn't really care about him buying the SS-400 system. After all, Turkey, and thus Nato, will also benefit from being able to discover more about the capabilities of the SS-400. And then the US can adapt the F-35 if necessary to thwart the Russian capabilities. I expect the Pentagon has thought of all of this and has mentioned this to the White House. So my guess is that Turkey will duly deploy its Russian S-400 system AND buy as many F-35s as it wants, provided Congress lifts the present suspension. Banning Turkey from buying F-35s would be madness. Erdogan will just turn once again to Moscow for its fighter fleet. Now that would be deeply embarrassing to the White House and to Nato. And Lockheed Martin, manufacturers of the F-35, would be sorely pissed off.