At the Wall Street Journal William Galston expresses the different views of North Korean motives pretty succinctly:
The success of nuclear diplomacy with North Korea depends on Pyongyang’s true motives for acquiring nuclear weapons, an issue about which the U.S. and China have long disagreed. Chinese experts and officials assert that the North has acquired a nuclear arsenal because the regime perceives a genuine threat from the U.S. and South Korea.
In a Brookings strategy paper, Fu Ying —chairman of the Foreign Affairs Committee of the National People’s Congress of China and a former lead participant in the multilateral talks about North Korea’s nuclear program—urges Americans to understand the profound sense of insecurity that pervaded the North Korean leadership after the collapse of the Soviet Union, which was for decades the regime’s principal supporter. Beijing’s move to establish full diplomatic relations with Seoul in 1992 intensified Pyongyang’s sense of isolation and probably strengthened its determination to depend on nuclear weapons rather than allies for security.
The view from Washington is very different. Most U.S. experts in and out of government believe North Korea’s pursuit of nuclear weapons reflects aggressive intentions—to push U.S. forces out of South Korea and reunify the peninsula on Pyongyang’s terms. North Korea’s ostensible security concerns, they say, stem from irrational paranoia about U.S. intentions that no concessions could allay. And North Korea’s history of reneging and cheating on interim agreements underscores the difficulty—if not outright futility—of returning once more to diplomacy. If the U.S. interpretation is correct, the only choices are deterrence, which implies acceptance of North Korea as a nuclear-armed state, or a disastrous war.
Unlike those, presumably including Mr. Galston, who hold the view that he attributes to the Chinese, I take the North Koreans at their word. “They can’t possibly mean it” is not a sound argument. However, there’s still a course of action other than deterrence or war. We could just tell the Chinese clearly and simply what the consequences of North Korean aggression would be: we would destroy the Kim regime and probably most of North Korea utterly and the Korean peninsula would be reunited under South Korea as an ally of the United States. If they’re content with that, just let the North Koreans keep doing what they’ve been doing. If they don’t like it, stop the North Koreans themselves.
That isn’t deterrence as the term is usually used, either aimed at North Korea or China. It’s merely a statement of the costs.