This article is BS. I know personally that the US Missile Command in Huntsville Alabama has ample access to the research and development for the entire Arrow Missile Program. Same goes for other allied research and development along the same lines of technology from both Germany and Japan. Maybe the truth lies in this article not being aware that there are more allied research efforts and the US military actaully has the fourth program... all independent of one another but assuredly with input from Israel, Germany and Japan the US program is the most advanced.
I believe the distinction here is that the Arrow contains both US funding and technology (Boeing) while the Iron Dome has little or no American technological input.