I'm playing a Hard campaign (RTW 1.5) and factions I'm about to destroy keep spawning hundreds upon hundreds of troops in their last two or three cities.

I've blockaded their ports, infiltrated their cities and sabotaged all of their training facilities, but when I hit end turn the city banners nevertheless leap up until they're nearly or entirely full. It's not even mercenary troops that appear!

Is there any way to play on Hard without the AI cheating so obviously? I don't want to go back to Normal difficulty because it isn't challenging enough.