@panzerbaguette Let’s look at this situation from the perspective of Japan. In order for France to declare war on Japan, in most games, it would require Germany to have declared war on a minor the turn before planning to take France out. For example, imagine Germany attacking Belgium in January, 1939 with a plan to take the double impulse against Warsaw and Paris in July, 1939. Germany is gambling that France and Great Britain won’t hit their Wartime Income with 2 D12’s each. France only needs to go up 9 (12 - 3 from the annexation of Austria, Bohemia, and Slovakia). The average of 2 D12’s is 13. Britain needs only to go up 11 (14 - 3 from the annexation of Austria, Bohemia, and Slovakia). In my hypothetical, Germany attacks Belgium in January, 1939; France rolls enough to get to Wartime Income and declares war on Japan?!? America’s Peacetime Income drops by 8 for this action! This will delay USA’s entry and really hurt the USA’s overall income through the course of the game. It’s not a one time penalty of -8. It’s turn after turn of having 8 less. This is absolutely fantastic for Japan and the USA and Commonwealth should try very hard to talk a French player out of making this mistake.
So you are probably talking about Japan declaring war on France early in the game, before France and Great Britain are aligned. This would increase the USA’s peacetime income by 5 D12’s. The average of 5 D12’s is 32.5! Remember how disastrous it would be to the Allies to subtract 8 from USA’s peacetime income? Imagine how game changing it would be to instead add 32.5 to USA’s peacetime income! You would be bringing USA into the war against you five turns early and you are doing that for the opportunity to do something against France?!? The Germans and Italians should strive mightily to convince Japan that would be foolishness.