International law and the Ukraine crisis

The US deputy security adviser has talked about the need for sanctions against Russia to be extended:

That is why it’s so important that sanctions are kept in place, so that they’re not just seen as one-time punishments that are then able to be waited out by countries that continue to violate international law and international norms. [1]

“International law” is the total corpus of UN Resolutions, treaties and to some extent principals which are generally accepted between nations. [2]

The line that Russian (or some other country who is not doing what the US wants) is breaking international law is a propaganda narrative line intended primarily for domestic consumption. The populations in “democracies” need to be constantly told that the