An international investigation concluded last week that the South Korean corvette Cheonan was sunk by a North Korean torpedo on March 26, killing forty-six South Korean sailors. In the wake of the investigation, South Korea suspended trade with North Korea, and the United States said it would participate in joint anti-submarine exercises with South Korea. But nothing will have much impact on North Korea without pressure from China, whose reticence is "not befitting of its proclaimed role as a rising power in Asia," says North Korea expert Victor D. Cha. Cha adds that the incident could be an "external manifestation of legitimization" on the part of North Korean leader Kim Jong-Il's chosen successor, his son Kim Jong-Un, or displeasure with a "conservative" South Korean government.

Why do you think North Korea might have done this?
Has this been a time of great tensions or what?

It's always difficult to divine North Korean intentions, mostly because it's the most opaque country in the world. But we can hazard educated guesses and a couple of potential explanations. The one you often see the most is that it's a direct retaliation for a surface ship altercation that took place in November 2009 in the Yellow Sea, in which one North Korean was reported killed. That's a tit-for-tat explanation.

Another is that the Kim Jong-Il regime is really unhappy with the conservative government in South Korea--that Pyongyang had become accustomed to ten years of Sunshine Policy under the previous two governments in South Korea, and they're not used to the current government's demands for reciprocity. If that explanation is accepted, this was essentially an attempt to stick it in the eye of the current government and say, "We're tougher than you, or you're not as tough as you think you are, and in the end you will come back and give us benefits because you, South Korea, have more invested in the peaceful status quo than we do."

A third explanation revolves around the succession question in North Korea, over who will succeed Kim Jong-Il, who is supposedly in poor health. This attack may in fact be an external manifestation of legitimization of the youngest son, Kim Jong-Un, as the next leader of North Korea. When Kim Jong-Il himself became the appointed successor to his father Kim Il-Sung, a similar sort of legitimization process took place in which Kim Jong-Il was responsible for many of the actions in the 1980s--such as the Korean Air 858 explosion in 1987, when North Korean agents planted a bomb in the plane which had taken off from Baghdad. The agents got off in Abu Dhabi, and the plane exploded over the Sea of Andaman, killing all 115 aboard. And in 1983 North Korean terrorists killed about half of the South Korean cabinet while it was on a state visit to Burma.

What we have seen in the past is that when these leaders don't have the revolutionary credentials of the original leader, [they] often use these sorts of events to legitimize themselves and to create a myth and history about their leadership.

Have we learned anything more about the youngest son?

We know very little about him. He's in his late twenties and apparently he studied abroad in Switzerland, and he is the one who has been seen as most likely to succeed Kim Jong-Il. He is still too young to lead, and if power were to pass it would probably be to him in combination with Kim Jong-Il's sister, Kim Kyung-Hee, and her husband, Chang Song-Eaek. Members of the military and party would be operating with the youngest son.

Does Kim Jung-Un have defense experience?

Not that we know of. We think he served in the military, but we don't know for sure. He has been seen at very low political levels of the National Defense Commission of the party in a way that we haven't seen him before.

The international report issued the other day says the Cheonan was sunk by a miniature sub, right?

Yes. From what we understand, the North Koreans sent a mother sub and some of the mini-submersibles out a couple of days before the incident happened. One of these semi-submersibles was on patrol near the Northern Limit Line, which is a maritime boundary between North and South Korea that the North Koreans often infiltrate. The submersible fired a torpedo that exploded about three meters underneath the ship, and it was the gas bubble and the air bubble from the explosion that broke the ship in half.

And they all returned back to their base?

Apparently two to three days later, they all returned back to their base.

North Korea denies it did it?

Yes. But this five-nation investigation involving the United States, Britain, Australia, Sweden, and South Korea had basically the three findings: that it was an external explosion that broke the ship; that it was a gas bubble from a torpedo that was the cause; and that the torpedo was clearly made in North Korea. They therefore deduced that there's really no other plausible explanation for the sinking of the ship than a North Korean torpedo. This wasn't a random altercation between the two. It was a clearly premeditated act. And it is the most serious act of aggression by the North against the South, military-to-military, since the end of the Korean War. I mean they've done terrorist acts that have killed more people, such as the airliner, but this is a clear violation of the armistice.

Secretary of State Hillary Clinton was in China at the time the report was issued, talking to the Chinese not only about the North Korean situation but getting Chinese cooperation on tough measures against Iran. Is what the Chinese say and do about North Korea important?

My immediate reaction was that the near-term objective has to have a response that reestablishes conventional deterrence on the peninsula. We do have a hard time stopping North Korea's nuclear and missile testing, but one thing we thought we were pretty good at was conventional deterrence. That is what has maintained peace on the peninsula for sixty years next month. And this very overt and major act of aggression may indicate that the North feels that as a nuclear weapons state it does not feel vulnerable any more. You've got to come up with measures that are tough enough so the North Koreans feel enough pain that they will not contemplate doing this sort of thing again without starting a war. From a policy perspective, that's the needle you have to thread.

The United States and South Korea announced things they are going do, cut off trade, U.S.-South Korean joint exercises. But none of this is going to really impact the regime in Pyongyang unless China exerts pressure. The Chinese thus far have been weak, clumsy, totally anachronistic in terms of how they've dealt with this.

What have the Chinese said so far?

All the Chinese have said is that this is an unfortunate incident. And all they've done is call for everybody to come back to Six Party Talks [North Korea, South Korea, China, the United States, Japan, and Russia] in Beijing aimed at ending North Korea's nuclear weapons program. None of those things achieves the near-term objective of establishing deterrence on the peninsula. The Chinese are so out of step with the international community on this, it's kind of ridiculous. And it's not befitting of its proclaimed role as a rising power in Asia.

Why are the Chinese so reluctant?

Part of it is that they're protecting their little Communist brother. They're still thinking in Cold War terms. And presumably, they want to ensure that the North doesn't collapse. But the thing to me that doesn't make a lot of sense here is that China may not want North Korea to collapse, but they also know that North Korea is not going to continue forever. They also know that their future is with South Korea. South Korea does $190 billion worth of business with China annually; the Chinese do $1.9 billion of business annually with North Korea. So it's one hundred times more with the South. They will say, "Now we have all these investments in mineral mines and other natural resources in North Korea," and they want to protect those investments. That also makes no sense, because once North Korea comes crumbling down, those contracts are going to be worth nothing, unless they deal with the South Korean government. The Chinese are supposed to think long term; what they're doing right now is not long-term thinking.

There's no way the United States and South Korea can go back to these Six Party Talks now, can they?

Pardon the pun, but I really think the North has torpedoed any chance of a resumption of Six Party Talks in the near future. It was reported before March 26, when the attack occurred, that there were quiet machinations going around trying to get back to the Six Party table. And it all came apart because of this North Korean action. The South Koreans have been pretty clear that they're not interested in coming back to the talks right now, and I think the Obama administration feels the same way.