It's really pathetic that we are more concerned with playing political games with our allies than fielding the best equipment for our armed forces.
Except that in many cases arming our allies to be able to fight off their immediate threats is much better for us than putting ourselves in a great position to be able to fight in their stead. I mean, which would you rather have: (a) a South Korean air force powerful enough to gain air control against North Korea, or (b) the US Air Force and Navy be forced to scramble a lot of their assets to Japan and fly long-range sorties from there while the North Koreans push the Southern army down to Busan?
Of course, this is not hypothetical; one of the reasons South Korea did so badly against the North in the first few days of the 1950 war was that the North had an air force and the South didn't. If the US Navy hadn't intervened promptly to provide carrier-based air patrol over Korea, the North Koreans would have won quickly.