All these decades of illegal behavior only serve to illustrate how meaningless these international laws are. Unenforceable law is as useful as a fart in a spacesuit.
Calling the process of annexing territory illegal is an exercise in hot air expulsion. Because frankly, the only way to prevent it or rectify it is to militarily defeat whoever is doing the annexing and remove the territory from their sovereignty.
Russia annexes Crimea. Its illegal....but so f**k what? Its annexed all the same and that's all there is to it. Calling it illegal is completely useless. Just words.