Actaea

You are attacking a country that is part of a military alliance with Kittypink.

That's up to Kittypink to decide. The Security Council, i.e., in this case, the international community, has come to the conclusion that what is happening in the Republic of Champignons is unacceptable and could become a major problem for everyone in the future. Kittypink can choose to cooperate and help resolve the "champignon problem," or it can go against everyone simply because it wants to.
Prevention is better than cure.