go to NATO HQ, you'll see vast numbers of documents, programmes etc.. with NOTUR written on them. it means not to be shown to, or discussed with, Turkish officers seconded to NATO. seasoned NATO watchers (and you thought train spotters were sad...) will have noted that many operations that theoeotically have a NATO flag on them are actually national/bi-national/multi-national operations by NATO members but not done through the machinery of NATO HQ's to keep sensitive information out of the grubby mitts of those countries within NATO that some other members of NATO don't trust as far as they could kick them.
relations are strained, and have been for at least a decade. they are still in NATO because it suits them to have a wall to hide behind if their plans go tits up, and it suits NATO to have them in - through gritted teeth - to keep a lid on any future Greece/Turkey squabbles, to have a buffer between mainland Europe and the ME, and to facilitate NATO intelligence gathering over the ME, Central Asia and the Caucuses and southern Russia.
we don't trust them, and they don't like our people being on the ground to see what they are upto...