I hate that "Remove or declare war". In my last game, I had just finished a war with Rome, and they had a few straggler units in my territory, I gave them a few turns, then said "Remove or declare war". War it is. This was bad for me, because I had just gone off War-Time, switched from Communism back to Democracy, and stopped producing units. I thought they weren't really going to fight, but I was wrong. They sent in a massive number of units, and I had to waste another 5 turns switching to Communism (I have bad experience with Democracy in long, drawn out wars).