Is there a way to take some aircraft and attack other aircraft? In this case I want to take my monoplanes to attack the AI's monoplanes so that I can then send my strategic bombers in safely.

Not sure that I remember correctly, but I think that fighter planes that are on patrol action work as anti-aircraft against bomber and fighter planes that are proactively used to bomb something. So, you can't do it directly, but you can keep your own planes in patrol mode to create an opportunity cost for bombing your districts and units. You could also try to bomb airdromes, I guess?

Yeah, there's no direct way to fight over air, aside of air-striking the base at which enemy interceptors are and that's extremely costly to do.

Thanks for the responses. It seems to me that this makes aircraft ineffective for offense as soon as the enemy has any aircraft of their own. Patrolling aircraft are, I believe, the strongest counter to attacking aircraft, and there's no decent counter to patrolling aircraft.

You also can add fighters to squadron of your bombers and bomb the enemies administrative center