“ Trump denied Turkey access to the F-35 program because they chose to install S400 systems from Russia.” this is true but please explain as well why turkey is

“ Trump denied Turkey access to the F-35 program because they chose to install S400 systems from Russia.” this is true but please explain as well why turkey is using S400 systems. Erdogan tried for years to get similar systems from the US and they never wanted to give it to turkey. Erdogan then rightfully bought S400 and this angered USA so much they removed turkey from F35; turkey then developed their own aircraft. lets also state that similar moves in drone technology years earlier by USA led turkey to become the world leader of modern drone warfare.