Ne milestone for me, I got sneak attacked when

[Bestbank Tiger]

my power wasn't Supreme.

I guess I was too far ahead in the space race. Fortunately I was able to build up a decent military quickly, and only lost one city (on an island well of my western coast). The Canadians got pimp-slapped on the mainland, and I had the UN so I was able to force them into a peace treaty. Then I put massive resources into defending my capital and building as fast a spaceship as possible, so I was able to win the game.

Then I kept playing and turned on cheat mode so I could put Barb nukes outside their cities. Take that!

 

[Sharwood]

You can be sneak attacked at any time, regardless of whether you're Supreme or not.