Lê_Đức_Thọ, who fought the US in Vietnam, got it in 1973 (together with Kissinger) and promptly refused it. Maybe the Nobel committee does not want to be embarrassed by a refusal again, and that is the only reason it no longer awards it to anti-western activists :)

https://en.wikipedia.org/wiki/L%C3%AA_%C4%90%E1%BB%A9c_Th%E1...