I was playing a multiplayer game with a friend with him as Russia and me as Germany. We agree to peace until 1942, and in 1940 I take over Poland/France. He takes over Latvia/Lithuania, and then heads onward to Finland. With these won, he declares war on Tibet in order to maintain the wartime bonus for two years so that he can get a bonus for when we go to war. I, spotting this after a year, declare war on Tibet and bring him into war against the Allies. Who is more in the wrong in this situation?