We can’t shoot down North Korea’s missiles

Tuesday, September 26th, 2017

The number one reason we don’t shoot down North Korea’s missiles is that we cannot:

Japanese Chief Cabinet Secretary Yoshihide Suga told his nation after last week’s test, “We didn’t intercept it because no damage to Japanese territory was expected.”

That is half true. The missile did not pose a serious threat. It flew over the Japanese island of Hokkaido, landing 3700 km (2300 miles) from its launch point near North Korea’s capital of Pyongyang.

The key word here is “over.” Like way over. Like 770 kilometers (475 miles) over Japan at the apogee of its flight path. Neither Japan nor the United States could have intercepted the missile. None of the theater ballistic missile defense weapons in existence can reach that high. It is hundreds of kilometers too high for the Aegis interceptors deployed on Navy ships off Japan. Even higher for the THAAD systems in South Korea and Guam. Way too high for the Patriot systems in Japan, which engage largely within the atmosphere.

All of these are basically designed to hit a missile in the post-mid-course or terminal phase, when it is on its way down, coming more or less straight at the defending system. Patriot is meant to protect relatively small areas such as ports or air bases; THAAD defends a larger area; the advanced Aegis system theoretically could defend thousands of square kilometers.

But could we intercept before the missile climbed that high? There is almost no chance of hitting a North Korean missile on its way up unless an Aegis ship was deployed very close to the launch point, perhaps in North Korean waters. Even then, it would have to chase the missile, a race it is unlikely to win. In the only one or two minutes of warning time any system would have, the probability of a successful engagement drops close to zero.


If North Korea cooperated and shot their new intercontinental ballistic missile, the Hwasong-14, at the United States with adequate warning so that we could prepare, and if the warhead looked pretty much like we expect it to look, and if they only shot one, and if they did not try to spoof the defense with decoys that looked like the warhead, or block the defense with low-power jammers, or hide the warhead in a cloud of chaff, or blind the defense by attacking the vulnerable radars, then, maybe this is true. The United States might have a 50-50 chance of hitting such a missile. If we had time to fire four or five interceptors, then the odds could go up.

But North Korea is unlikely to cooperate. It will do everything possible to suppress the defenses. The 1999 National Intelligence Estimate of the Ballistic Threat to the United States noted that any country capable of testing a long-range ballistic missile would “rely initially on readily available technology – including separating RVs [reentry vehicles], spin-stabilized RVs, RV reorientation, radar absorbing material, booster fragmentation, low-power jammers, chaff, and simple (balloon) decoys – to develop penetration aids and countermeasures.”

Our anti-missile systems have never been realistically tested against any of these simple countermeasures.


  1. Bob Sykes says:

    Actually, our anti-missile systems have never been realistically tested. Every “test” was scheduled, scripted, with a known launch point and a known target. No counter measures were ever employed.

    A real test would be for some sub commander to launch a missile unannounced, from a secret location at a secret target. I suspect the defensive system wouldn’t even notice the launch until the test was over.

    Real missile defenses would have to be manned and on alert 24/7, and the anti-missile missile would have to be “on the pad” primed and ready to go on a moment’s notice. Considering the variety of possible incoming missiles and their launch points and targets, an anti-missile defense is probably impossible. Even Sidewinder anti-aircraft missiles, now in use and under development for decades, miss most of the time, just recently in Syria.

  2. Wilson says:

    If we had the capability, on the other hand, there would be an arms race with other not-so-friendly nuclear states, which increases the risk of mistakes

  3. On a number of points, the author is either confused or mendacious (as he is president of the Ploughshares Fund, I’m betting the latter).

    The key word here is “over.” … Like 770 kilometers (475 miles) over Japan at the apogee of its flight path. Neither Japan nor the United States could have intercepted the missile. None of the theater ballistic missile defense weapons in existence can reach that high. It is hundreds of kilometers too high for the Aegis interceptors deployed on Navy ships off Japan. Even higher for the THAAD systems in South Korea and Guam. Way too high for the Patriot systems in Japan, which engage largely within the atmosphere.

    True but completely irrelevant. All of those systems engage the missile in the terminal phase. If it had been an attack, then the missile would have had to actually come down on the target and thus into range of engagement.

    …coming more or less straight at the defending system.

    Skillful use of weasel words, there.

    Then we have a bit about how missiles not designed or intended for boost-phase intercept are, quelle surprise not very good at boost-phase intercept.

    THAAD would have a chance to engage, though it has only been tested once against a missile of this range.

    He pointedly avoids mentioning that it was a successful test (and a rather realistic one), and that the attacking missile’s range means little to that type of point-defense interception.

    For the test flights over Japan that would mean the only engagements possible are to the east of Japan… But there is little reason and huge logistical difficulties in having U.S. Aegis destroyers and cruisers loiter in the ocean there, waiting…

    This is what decides it in favor of mendaciousness for me. There’s some sort of problem with having our BMD-capable ships in the Sea of Japan? He might want to tell that to SM-3 equipped ships we have doing regular patrols through those waters, ships indeed homeported in Japan. Then he talks about how hard it would be to stop one of the test-overflights of Japan, but carefully avoids mentioning that it would be much easier to stop an actual attack.

    We then switch to discussing mid-course interception with GBMD. Of the various PenAids he discusses, most aren’t very effective against mid-course interception. He also stays true to a hoary tradition among disingenuous critics of ABM: always intimate that any improvement to defensive systems is fraught with cost and peril, while any improvement to an opponent’s offensive system is effortless and inexpensive. Of course, in practice that’s very much not the case.

    We could … begin testing for actual performance, with “red team – blue team” tests, for example, to simulate a determined foe.

    Finally, something I can wholeheartedly agree with. It’s shameful that we haven’t sprung for much more extensive testing of GBMD in particular. And while we’re at it we should get the operational-version STSS constellation launched posthaste, which would put to bed concerns about chaff and decoys.

  4. Bob, if you think about the geometry of a mid-course intercept you’ll see that there aren’t actually a lot of variations such a system needs to deal with. With launch silos in Alaska and California for GBMD, any ICBM launch from the east represents a closing-target engagement for one or the other site. There thus isn’t much point to hidden-launch/hidden-target tests until very late in the test sequence (which doesn’t mean we shouldn’t do them).

    There’s no particular conceptual or fundamental difficulty with mid-course intercept against ICBMs. The four key requirements are:

    1) Good early warning. We have this in the form of SBIR.

    2) Good target acquisition and whole-trajectory tracking. We’re weaker on this, as the sea-based X-band radar project has had serious issues and we haven’t gotten around to launching the STSS satellites yet, despite proving the demo versions worked several years ago. That said, for attacks on the continental US, PAVE PAWS is probably good enough for most situations.

    3) A booster with plenty of delta-V to loft the interceptor. This isn’t a problem, with the requirements no greater than those of an ICBM and typically rather less.

    4) An interceptor that can do the fine maneuvering necessary to impact the ICBM’s bus (the advantage of mid-course intercept is that you hit the bus before it can disgorge its warheads, decoys, etc.). I’d say we need much more testing of this, and under more realistic conditions. It’s a little spacecraft, in effect, and a pretty complicated piece of hardware.

    If you look at the testing history of GBMD, you’ll find that the test failures are primarily the sort of things that always go wrong with a new piece of complicated military equipment, mainly component and system failures. There’s nothing that can’t be fixed with more extensive testing and iteration.

    On a more general note about testing, there are two common misconceptions. First, that controlled-environment testing is somehow not really a good test. The issue with this is that for a good chunk of the program what you’re testing is the performance of specific parts of the system. If we’re running a test of an interceptor it doesn’t make sense to set things up such that some other part of the system might fail and deny the chance to even use the interceptor. Generally you should see tests proceed from component and sub-system up through very controlled whole-system tests, then a series of increasingly challenging and realistic tests to cap the program off.

    It also doesn’t make sense to skip ahead if you haven’t yet ironed out the kings in the components and the obvious problems with the system. With GBMD we simply haven’t done enough tests yet to get to the point where the higher realism ones are justified. As of the last few, they were still working on perfecting the interceptor among other things.

    Second, there’s an idea that if tests don’t show a very high success rate then the system is a failure. The problem here is that a well-designed test sequence will always be pushing the system just to the point that it doesn’t work, alternating with the occasional run designed to make sure that the problem identified in the last failed test is actually rectified. If you see a system with a very high success rate in tests it should not fill you with confidence, quite the opposite.

    Lastly, the point about AIM-9 isn’t really valid here. Yes, missiles always underperform their stated Pkill, but the AIM-9 is employed in an extremely demanding and variable environment where it has to deal with shocks, vibration, extreme and variable g-load, and a host of other issues that an ABM missile doesn’t have to, and the design faces severe constraints due to the need for miniaturization.

    I wonder, though. In Vietnam and the Gulf War the USAF and USN saw a ~1/5 Pkill for AIM-9, despite the the use of very different versions of the missile in the two conflicts. At the same time, the British somehow managed a ~4/5 Pkill using AIM-9L in the Falklands. Possibly a difference in employment? It probably bears more study.

  5. I am become Kirk, destroyer of wordcount limits.

  6. Kirk says:

    Catharsis is good, isn’t it? ;)

Leave a Reply