I have doubts about this being a good way to say it in English, because it would seem to me to mean "the positions of MPs in NATO".
(However, I simply don't know and this might be the correct way to express it)
I undestand that kannat are positions in the sense of opinions or points of view.
Although I do not understand it completely, as the graphs on the web say kyllä/ei - but what is the question that is being answered with yes/no? Within the context it is clear, but perhaps kannat also means support? Then answers yes/no would also be clear in any context, meaning voting yes/no for any support.
Were there other kannat in the parliament, other than Nato-kannat ? Is it a common procedure? If a procedure at all...