It my be just a cr but i believe it's a bug. While declearing war, the oponent tribe automatically becomes you enemy and is threat like this on the map, it is marked as enemy. This tribe can invite other tribes to join their alliance. If they do, they do not become automatically enemies.
Steps to reproduce:
Declare war. The oponent tribe must invite other tribes and these have to join the war.
Reproduction rate (Every time? Sometimes?):
every time
Browser and Version:
FF26.0
Visual Reference if available (Screenshot) please put them in a spoiler.: