North Korea’s announcement of an impending nuclear test refers to a “a nuclear test of higher level which will be carried out by it in the upcoming all-out action…”  Most people seem to be focusing on the possibility of a device using highly enriched uranium — which is probably right but maybe not the whole story.

DPRK officials have been dropping some interesting hints lately.  In August, the DPRK indicated that it would be “modernizing and expanding its nuclear deterrent capability beyond the U.S. imagination.”  That would seem to suggest we should should broaden our realm of possibilities.

I’ve been thinking about the possibility of a North Korean thermonuclear weapons test since 2010, after North Korea started talking about Korean style thermo-nuclear reaction devices.  (Not quite as catchy as Gangnam Style, eh?) Apparently, I am no longer the only crank.  The Asahi Shimbun recently published an article entitled, ”DPRK Likely To Use ‘Fusion-Boosted Fission Bomb’ in Third Nuclear Test.” Tony Namkung, who took Google’s Eric Schmidt to North Korea, has said that it “will this time be a thermonuclear test.”  He must have had some interesting conversations in Pyongyang.

Sounds crazy, I know.  But I think we have to at least consider an early DPRK effort at a thermonuclear weapon of one sort or another.  (I am still inclined to think a boosted design like the Alarm Clock is more likely than a staged device.)  We’ve systematically underestimated both North Korea’s capabilities and, even when those capabilities are found wanting, the leadership’s resolve to try anyway.

I’ve been thinking about this possibility again for at least three reasons:

First, the more I think about the film The Country I Saw (for a summary, reread the piece I wrote with Hanah Rhee for 38North), the more I think thermonuclear weapons are the obvious goal for North Korea.  It sounds strange, perhaps, but thermonuclear weapons were the Chinese goal as early as the late 1950s. In 2002, Kang Sok-ju told Jim Kelly responded to evidence that North Korea was pursuing uranium enrichment by stating that North Korea was ”entitled to possess our own HEU, and we are bound to produce more powerful weapons than that.” Kang may have committed the canonical diplomatic gaffe — saying what he really thought. (Tong Kim certainly thought, in context, he was talking about thermonuclear weapons.) Also, if Kim Jong Il wanted to bequeath his son some technical accomplishments to make his first year or so in power an eventful one, putting a satellite in orbit, testing an ICBM and detonating a thermonuclear weapon seem like pretty solid ideas. We may wonder about North Korea’s technical capability, but I don’t think the North Korean leadership will simply settle for a small number of relatively crude fission-type devices.

Second, consider North Korea’s statement following its 2009 nuclear test:

The current nuclear test was safely conducted on a new higher level in terms of its explosive power and technology of its control and the results of the test helped satisfactorily settle the scientific and technological problems arising in further increasing the power of nuclear weapons and steadily developing nuclear technology.

“Higher level” explicitly refers to both yield and technology.  What is really interesting, though, is the statement of purpose: “the results of the test helped satisfactorily settle the scientific and technological problems arising in further increasing the power of nuclear weapons and steadily developing nuclear technology.” KCNA could not have been more clear that these tests were leading to something larger. Tom Schelling likes to point out that many first nuclear tests are better described as “demonstrations” than tests. He’s right, but the North Koreans are going out of their way to make it clear that their nuclear events are both.

Third, the North Koreans themselves have been talking more about thermonuclear weapons, and thermonuclear war, in recent months.  In addition to the August statement, North Korean Vice Foreign Minister Pak Kil-yon said in October  that:

Today, due to the continued U.S. hostile policy towards DPRK, the vicious cycle of confrontation and aggravation of tensions is an ongoing phenomenon on the Korean peninsula, which has become the world’s most dangerous hot spot where a spark of fire could set off a thermonuclear war.

I don’t think Pak is describing a war in which the DPRK are the only thermonuclear victims. I’ve gone back and forth over whether to mention that Kim Myong Chol, an “unofficial spokesman” for the DPRK, has been saying that the DPRK is developing thermonuclear weapons for years.  Kim isn’t privy to such details and uncritically repeats any claim he reads in Western media that suit his particular bromide of the moment.  (His source on North Korea’s thermonuclear weapons seems to be John Pike.) I am going to stick with state media and DPRK officials, while adding that KCNA repeated Kim’s assertion that “Unlike the past Korean War which was limited to the Korean Peninsula, the second Korean War will turn into a thermonuclear war and naturally spill over into the U.S. mainland.” Whether or not Kim is right about the particulars, the party line seems to be that North Korea won’t be the only victims in a thermonuclear war.

Given all this, we should at least consider the possibility that, in addition to testing an HEU-based device, the North Koreans may burn a fusion fuel like Lithium 6. China detonated a 250-kiloton thermonuclear device on its third test, after a design program that lasted little more than a year. India conducted one test in 1974. Then, on May 11, 1998, India conducted three simultaneous nuclear tests — one of which they claimed was a thermonuclear weapon. (India conducted two more tests on May 13.) There are lots of reasons to believe that India’s H-bomb was a disappointment, but North Korea has hardly been deterred from testing by the prospect of failure. Our friends in Israel seem to have a thermonuclear weapon of one sort or another with no known tests, plus whatever might have happened on September 22, 1979.

If the US intelligence community thinks this is even a possibility, the Obama Administration should be managing expectations with allies now as Bob Gates did with the KN-08.  It would help to emphasize that bigger nuclear weapons wouldn’t really change our commitment to the defense of Japan and South Korea and that it would be suicide for North Korea to use a nuclear weapons of any kind.

I don’t want to be alarmist.  North Korea might simply test an HEU device or maybe a more efficient missile warhead.  If they do try something fancier, it may not work — which means we might never know what it was. But it is important to understand that the range of North Korean possibilities may be much larger than we normally describe.  We are not likely to get more hints than we have now, unless the DPRK publishes a picture of Kim Jong Un holding a soccer ball with a Teller-Ulam device drawn on a blackboard or starts sending scientists to international conferences with papers on thermonuclear fusion.