Article 6 of the NATO treaty specifically mentions the Mediterranean Sea, but not the Baltic Sea. So do NATO countries consider an attack on their aircraft or vessels in the Baltic Sea, but in international waters thereof, as falling under the area covered by the NATO treaty? (There's always the more vague "North Atlantic area north of the Tropic of Cancer" as the catch-all in the end). I'm guessing this issue of the Baltic Sea might have come up during the treaty drafting or later in some later, post-treaty discussions.