Kosovo was a bad idea, based on the notion that the UN system could legitimize exceptions. Berlin and Paris warned about, it London and Washington pushed ahead with it, getting the sceptic French and Germans governments to acquiesce.
If there is a take-away, it is that everyone has been listening FAR too much to what Washington and London has been saying for far too long. It's another version of the long shadow cast by WWII – just like the current Russian homicidal idiocy also is, if of a different timbre.
The US "coalition of the willing", never mind the total debacle that is the Guantanamo prisoner situation, was a disaster. Part of the reason Putin is peeing on the UN and its principles clearly is the spectacle of the US doing what it has been doing – turbo-charged by the Trump presidency, indicating that clearly the US is not a reliable guarantor of anything is otherwise professes.
But the US BS was in trying to make exceptions, to make them limited and with NO precedence status, putting expediency over principle. I have zero problem with how the US GWB government should be on trial for what it did. That's not the issue. What is the issue is it is impossible to limit these exceptions so that they will not have precedence status as soon as someone claims it – which is the whole Russia argument over Kosovo here. But that also means that if Putin argues that he can unilaterally declare parts of Ukraine Russian, and his "words are backed by nuclear weapons", then that ALSO is not a limited exception – that IS the principle.
Putin is deliberately doing something that will reduce the principles of the UN to at best dead letters. Now, someone like Kyr might want to argue that due to all of the above, it already IS dead letters anyway. I.e. he doesn't think there is anything in the UN system to salvage anyway. Others may disagree however.
And that still begs the question in what way we are better off with letting Russia get away with what Putin is trying here? Why would accepting this "exception" be a good thing, or even just necessary? Especially since it is NOT an exception, but a new rule, if Putin gets things his way.
And so the matter will not be decided in the UN, or through a negotiated solution, but on the battlefield.