Nato

Factual Questions
1

why is it that the secretary general of nato has always been an american? is it simply because the u.s. is the most dominant power in nato, or was it a pre-condition for the u.s.’ involvement in nato?

2

From here:

So it seems there has never been an American Secretary General of NATO.

However, the Supreme Allied Commander, Europe has always been an American, most likely because the US contributes the largest military force to NATO.

3

Friedo beat me to it. My link has pictures. As though that were worth anything.