The AI as Big Brother

[Castellon]

I'm not so sure. Size of the armies of the major powers (human players included) is available for a human player (it's displayed in one of the graphs), so if I'm given knowledge of the buildup of AI armies, why shouldn't it be given the same knowledge about my size of the armies.
Although certainly AI doesn't use this knowledge even if has it - it's only going to start building armies (in most cases) once the war breaks.

It is self evident that the AI knows the size of your army and uses that info in it's decision making.

Just have poor relations with a nation and delete your whole army, then see what happens.