"There is no question that the political and security implications of the [recent North Korean nuclear] test are huge and almost entirely negative," writes Ivan Oelrich, over at the Strategic Security Blog. "The technical significance of the test is somewhat less than meets the eye."
[A week ago,] the outside world knew that the North Koreans had plutonium available from fuel rods that had been removed from the reactor at Yongbyon. We knew that at least some of the plutonium had been separated out of the fuel rods and, since separation is a fairly straightforward process, it was a fair assumption that most or all of the plutonium had been separated. So we knew about their plutonium supply (and the test tells us nothing more about that), but another key question remained: Could they fashion the plutonium into a bomb?...Before the test, we did not know whether the North Koreans could build an implosion bomb or not. Had the test been successful, we would now know that they could, although we would still not know how close they were to a useable weapon; their test device might have weighed tons and been a once off, rigged up, laboratory experiment. But the test was not successful, so we still dont know whether the North Koreans can build a workable implosion bomb. Presumably the North Koreans learned something from the test so the probability of the next test being successful is somewhat higher than the probability that the first test would have been successful. This is not much of difference, leaving us in pretty much the same position we were in before the test...Why might the test have failed? An implosion bomb uses conventional high explosives to compress plutonium until it becomes critical, that is, it will sustain a run-away chain reaction. The pressure from the conventional explosives has to be carefully controlled, for example, it must be symmetric or else it is like squeezing a ball of putty: pressure on one side doesnt compress the plutonium, it just squirts it out the other side. The most likely reason for the failure is some problem with the compression and there is any number of reasons why the compression might not be adequate. If the test were carefully instrumented (which is not necessarily the case), the North Koreans should be able to narrow down the cause, which will give them a much improved chance for success with their next test.UPDATE 10/14/06 11:20 AM: "Initial environmental samples collected by a U.S. military aircraft detected signs of radiation over the Sea of Japan, possibly confirming North Korea's nuclear test," the Washington Post reports.UPDATE 10/15/06 7:06 PM: "The proposition that the apparently low yield of the test is a failure is not self evident," says Defense Tech pal John Pike, pointing to this Weekly Standard piece. After all, Pike notes, the yield on the American B61 nuke can range anywhere from a third of a kiloton to more than 350 kt.UPDATE 10/15/06 7:23 PM: No excerpt will do justice to this epic retelling of North Korea 50-year quest for the Bomb. So just go and read the whole thing.