Jim Dunnigan argues that it’s not yet time to lose sleep over North Korean nukes:
Most of the missiles available to the new nuclear powers can carry a half ton warhead. The U.S. had such warheads in service by 1954. But to do so required a lot more scientific and engineering talent than the new nuclear powers have. In addition, the bomb developers were able to test their designs. While powerful computers make it possible to do “virtual tests,” the new nuclear nations do not have access to the super-fast computers needed for this kind of testing. Perhaps more importantly, these new nuclear powers do not have access to the data from tests that were simulated, then run with a real weapon. In other words, you need to either do live tests, or have very expensive supercomputers, and the right software, to make sure your smaller warheads work. While China may have stolen a lot of the secret U.S. data on smaller nuclear warheads, it uncertain if any of that information has been passed on. In the end, you don’t have to get worried about North Korean or Iranian nuclear weapons unless there is news of smaller warheads that work.
Then again, it hardly takes an ICBM to deliver a bomb across the border into Iraq or South Korea.