They’re responsible for honoring their agreements and contracts. How can any European state now trust the F-35s that they’ve purchased or going to purchase? All the trans-Atlantic trust built since 1945. Flushed down the toilet in a few weeks. Trust is difficult to build but easy to destroy.
To be fair, as a true fifth-gen fighter the F-35 absolutely does have capabilities no European one does. It is an impressive piece of hardware, and the US has been selling them for quite reasonable prices.