There isn't any debate that this is NATO's policy. It is frequently discussed during the application process for many nations. However, the application process itself is even more explicit, since you still seem skeptical (despite what numerous foreign policy, military, political scientists indicate).
"Aspirants would also be expected:
...
to settle ethnic disputes or external territorial disputes including irredentist claims or internal jurisdictional disputes by peaceful means in accordance with OSCE principles and to pursue good neighbourly relations;"
"Aspirants would also be expected: ... to settle ethnic disputes or external territorial disputes including irredentist claims or internal jurisdictional disputes by peaceful means in accordance with OSCE principles and to pursue good neighbourly relations;"