What was the international legal basis for keeping the planes?

HOW DO YOU RETURN PLANES DURING A HOT WAR? Listen to your fucking self. The legal basis for keeping the planes is that LEASES are nothing but contracts and international contract law relies on good standing between the parties. Without a court that would be willing to actual rule on the contracts, the contracts are essentially nullified during a hot war and it will only be AFTER the war that the winning court system will decide on how to proceed with the violation of a private agreement across international borders with completely different legal regimes.

like I say, I think this style of argumentation is mostly a waste of time.

It is, but not for the reason you believe, though.

I came in more or less agreeing with you on a topic we should be roughly on the same side of, but you clearly don’t want that – I think you just want someone to play to role of your enemy so you can be hostile at them.

You're psychologizing me, creating a fantasy of who am I and how I think and what I want so that you can make sense of why someone would be so irate with someone like you, who clearly has faults but never really deserves to be pushed so hard, because your heart is in the right place. Fuck off.