What do the green and red X and yellow circle represent during the strikes in a war

I know what the international standard is for the colors red and green (stop and go). But during a strike, who or what displays the colors? Does the person in charge of the alliance manipulate it for the benefit of people in the alliance? Or does a computer program do it. And does both the attacker and the defender see the same thing? Or does the defender see the opposite of what the attacker sees. And what does the yellow circle stand for? Am I right to assume the colors are guidelines to let people know when they are either winning or losing by a large margin? 

You could ask them you know…

(the answer is yes)

Hello there,

Captain, Officers, Generals and the Founder can set the war markers. Only your own alliance sees it, not the enemy alliances. The yellow circle is neutral, the alliance can decide what to use it for. This should make it easier to communicate which islands shall be attacked and which to ignore.