Historically Korea had been a loyal vassal state of China for thousands of year. China had defended Korea against various barbarians from Mongolia plateau, Japa

Historically Korea had been a loyal vassal state of China for thousands of year. China had defended Korea against various barbarians from Mongolia plateau, Japan(multiple times) and America more recently. The reason NK still exists is not USA's mercy or NK's nuke, it's because it's neighboring with China & Russia. Same thing applies to Vietnam.