Thank you for the question.
NATO is an association of sovereign nations. Nations take their own decisions for their own reasons in the first instance. So there has never been.... I think NATO dreams of such coherence of approach, that NATO nations as a community would say they're all going to this particular supplier for this particular widget. It just doesn't happen that way, because nations take their own decisions.
What nations do is they take into consideration their desire—and that could be on a spectrum of little desire to a lot of desire—to make sure that whatever it is they're getting is going to allow them to, as Brian says, plug and play, to be able to actually join up with others and do things together because they use the same fuel or the same ammunition or they can speak on the same radios.
But NATO is fiercely an alliance of sovereign states in the first instance.