Continents in this context are political/cultural/ethnic continents, not actual geological ones. There is no geological distinction between Europe and most of Asia (though for some reason it is common for us to remove India and the Arabic countries from the Eurasian continent by calling them the Indian subcontinent and Middle East even though they are culturally and ethnically more similar to the rest of Asia than Turkey is, but they do sit on their own continental plates). IMO we need to pick a method for identifying continents and stick to it. Most NATO members are on the Eurasian supercontinent. Turkey is in a political/cultural/ethnic grey area of what we have arbitrarily decided were the European, Middle Eastern and Asian "continents".