Russia has supplied the s400 air defense missile system to Turkey, and Turkey is obviously very happy about it. The United States is very angry with Turkey, because the United States has always regarded Russia as an opponent, and Turkey's choice of Russian air defense missile system means being an enemy of the United States, and these three countries will thus form a very embarrassing situation. In the face of such a situation, the United States will naturally not sell its own fighter planes to Turkey in a friendly way.
Later, the Pentagon also publicly warned Turkey that if Turkey dared to sign the s400 air defense missile system contract with Russia, the United States would refuse to sell F35 stealth fighters and Patriot air defense missiles to Turkey, and the 100 F35 fighters that Turkey had previously ordered from the United States would also be detained. It can be seen that the United States is obviously very angry with Turkey's practice and even began to threaten Turkey. These fighters that Turkey has spent billions of dollars to buy from the United States will also suffer huge losses.
In the face of Trump's non-compliance with the contract and threatening his own behavior, Turkey clearly saw the intention of the United States, but at the same time Erdogan also made it clear to Russia that he would definitely sign the s400 air defense missile system with him, and made it clear to the United States in a friendly way that he was willing to continue negotiations with the United States on the purchase of fighter jets.