Inviolability of Ukraine's territory and sovereignty

I read that Ukraine's representative to the UN emphasized: our country does not trade in territory or sovereignty, and there is no point in even hoping for that – this is a matter of principle. I am interested in whether any international negotiations or agreements could lead to a part of Ukraine's territory being officially recognized as non-Ukrainian? And if so, do I, as a citizen, have the right to do anything in such a situation, for example, appeal to a court or the authorities?