North Korea’s potential intercontinental ballistic missile (ICBM) threat may be stealing headlines, but the rogue state’s interest in submarine-launched nuclear weapons is arguably even more worrisome.
That’s because unlike land-based ICBMs — which are not so easily hidden from satellite surveillance — submarine-launched missiles can, in principle, be moved about at will. And even though such missiles have much shorter ranges, they do have the ability to achieve some level of stealth off an adversary’s populated coastline.
To that end, in the past three years, North Korea has specifically been working on a submarine-launched ballistic missile, Joseph Bermudez, a longtime North Korea hand and the chief analytical officer at All Source Analysis in Longmont, Colo., told me. In 2014, he says North Korea launched its first experimental ballistic missile submarine and they have had at least two trials of a submarine-launched missile, one of which appears to have failed.
However Bermudez guesses it would have a likely range of some tens to a few hundreds of miles. But he points out that the sort of submarine-launch systems North Korea is attempting are hardly advanced by Western standards. Instead, Bermudez says they most closely resemble first-generation Chinese submarine-launch systems.
But despite such setbacks, North Korea is making progress in its quest for means of delivering its potential arsenal of an estimated dozen or so plutonium-based nuclear devices. None are thought to have explosive yields larger than 15 to 20 kilotons; similar to the bombs dropped on Hiroshima and Nagasaki more than 60 years ago. Yet perhaps, even more importantly, North Korea apparently still lacks the ability to miniaturize such devices into warheads capable of being mounted on any sort of long-range ballistic missile.
The Unha-3 launcher, however, remains largely based on 1960s-era Soviet Scud-type technology, David Wright, a physicist and co-director of the global security program at the Union of Concerned Scientists in Cambridge, Mass., told me. Wright emphasizes that such technology is not generally used for long-range missiles because it is inherently inefficient.
“We have never seen them flight-test a missile with the kind of large engines you need for the lower stages of a missile,” said Wright.
But this most recent satellite launch became an impromptu foreign policy test for several of the Republican presidential contenders at their New Hampshire debate. That is, on whether the U.S. should preemptively strike to take out a North Korean ICBM.
“Unless we have very strong intelligence that there’s a warhead on a [North Korean] launch pad aimed at us, we would likely have a tough time legitimizing any attack to take it out,” a senior civilian analyst with the U.S. Navy told me on condition of anonymity. “It would be an act of war.”
However, the analyst added that China itself might act to stop North Korea in such a scenario; noting that “the last thing China wants is war between their neighbor and the U.S.”
Meanwhile, the U.S. can take some comfort in the fact that North Korea is still struggling with the basic aerospace technology needed to deliver such weapons.
When launching a ballistic missile, Bermudez says, the warhead immediately experiences tremendous G-forces, vibrations, heating and cooling as it exits and re-enters Earth’s atmosphere. All these things make it tough to design a nuclear warhead that is functional over that entire range, he says.
When could North Korea be capable of producing an ICBM capable of striking San Francisco or Los Angeles?
North Korea would need to build a bigger or more advanced missile and/or reduce the mass of its nuclear warhead, says Wright. If they modified the Unha-3 launcher and developed and tested a re-entry heat shield, he says, North Korea might be able to send a 500-kg weapon to the U.S.
“It is difficult to predict when they will make these advances but I think it will take years,” said Wright.
As for the U.S.’ ability to intercept such missiles once launched?
Wright says the Defense Department’s Missile Defense Agency (MDA) currently has some thirty missile interceptors as part of its Ground-based Midcourse Defense (GMD) system; mostly housed in silos in Alaska, with a few in California. However, the GMD system — which is designed to intercept incoming intermediate and long-range ballistic missiles before re-entry into Earth’s atmosphere — only began deploying in 2004.
“The GMD system is still in the relatively early stages of testing and has only been successful half the time,” said Wright. “The data is simply not there to say the GMD system could stop an attack. Despite the fact that government officials make that claim, GMD has no demonstrated capability to stop an attack on the U.S.”