Reliability is in the Eye of the Beholder: The Value of North Korea’s Freeze on Further ICBM Flight Testing

(Photo: KCNA)

North Korea has conducted a total of three apparently successful flight tests of its two intercontinental ballistic missiles (ICBMs) but has observed a unilateral moratorium on long-range ballistic missile tests since early 2018. By the traditional missile development and deployment standards of the US, the Soviet Union/Russia, and even China, one or two tests of an ICBM (even if successful) would not establish sufficient confidence in effective wartime operation for deployment as part of the North’s highly critical nuclear deterrent. Rather, these countries have historically conducted from one dozen to three dozen tests of an ICBM system before deployment. The contrast between DPRK claims and these standards raises three key questions that this article will explore:

  • Would North Korea really have deployed nuclear-armed ICBMs based on the current amount of flight testing?
  • How reliable could such an ICBM force be, and what value could it provide?
  • Does an ICBM flight-test moratorium or a future negotiated flight-test ban have value if North Korea has already deployed ICBMs?

It is credible that North Korea would deploy nuclear-armed ICBMs based on the current amount of flight testing, given likely North Korean standards. Even so, preventing further flight tests has considerable security value for the US, in part because it will probably prevent the DPRK from improving current ICBM reliability appreciably over time. Steps to induce North Korea to continue its current moratorium, or formalize it as part of a negotiated agreement, therefore, should be a US priority.

Deployment with Little Testing

Despite having conducted so few ICBM launches (and only detonating six nuclear devices), on January 1, 2018, Kim Jong Un essentially claimed to have a deployed, nuclear-armed ICBM force: “The whole of its mainland is within the range of our nuclear strike and the nuclear button is on my office desk all the time; the United States needs to be clearly aware that this is not merely a threat but a reality.”[1] This claim also is consistent with Kim’s April 2018 report to the Korean Workers’ Party Central Committee that “…no nuclear test and intermediate-range and inter-continental ballistic rocket test-fire are necessary for the DPRK now, given that the work for mounting nuclear warheads on ballistic rockets was finished…” Given that Kim is prone to hyperbole, what are we to make of these claims?

It is credible that North Korea would deploy nuclear-armed ICBMs based on the current amount of flight testing. Western assessments of the history of North Korea’s missile program indicate that the DPRK has almost always deployed ballistic missiles after far fewer flight tests than other countries—and in two cases, perhaps with no flight tests:[2]

  • North Korea reportedly deployed its version of the Scud-B short-range ballistic missile (SRBM) in 1986 after some six flight tests (three successful).
  • The Scud-C SRBM was reportedly deployed in 1992 after some two flight tests (both successful).
  • The Nodong medium-range ballistic missile (MRBM) was reportedly deployed in 1994-1995 after three flight tests (one successful).
  • There are some reports that the Musudan intermediate-range ballistic missile (IRBM) was deployed in the early 2000s,[3] long before its first launch (a failure) in 2016. The missile ultimately was launched eight times, with only one success.
  • The Toksa/KN-02 solid-propellant SRBM was reportedly deployed in 2006-2008, if not earlier, long before flight testing apparently began in 2013. (Since 2013, there have been 20 launches, all apparently successful.)

Deployment also is consistent with open-source reports that the DPRK has been producing ICBMs, and building or improving missile bases suitable for ICBMs, since the last flight test.

Reliability and Value of ICBMs with Little Testing

Despite the apparent successful flight tests to date, North Korea’s ICBMs currently are almost certainly not highly reliable. (For example, the missiles were only tested on steep trajectories rather than to full range.[4]) But the DPRK probably regards these ICBMs as sufficiently reliable for the current purposes for which North Korea would be deploying them. At a minimum, Pyongyang would see the advantages to date in forgoing further flight testing as outweighing the limitations this places on its ICBM force.

We do not know how reliable the DPRK thinks its ICBMs are; it probably does not really know given the current number of flight tests.[5] One analyst assessed that it could not even be confident of a 50 percent success rate under these circumstances.[6] But the North almost certainly gauges the current value and reliability of its ICBMs using North Korean standards, which probably are significantly lower than those of the US and USSR during the Cold War.[7] This makes sense given the substantial differences in the DPRK’s historic flight testing and deployment practices and its circumstances. Pyongyang probably:

  • Does not perceive a substantial risk of a “bolt from the blue” nuclear attack against itself under day-to-day circumstances;
  • Believes a substantial increase in that risk would be preceded by an identifiable and relatively lengthy period of tension; and
  • Is unlikely to be interested in nuclear warfighting or counterforce targeting during wartime, which demand more reliable ICBMs.

We do not know the DPRK’s intended purposes for its ICBMs, how those purposes are affected by reliability, or how reliance on ICBMs with so few tests might affect its future crisis or wartime calculations. But such ICBMs do appear to have value in North Korea’s current situation:

  • “Emergency” Use: ICBMs with a reliability “close enough for [DPRK] government work” would be available for use against large US metropolitan areas if Kim Jong Un believed in the future that his regime’s existence was at stake or confronted other dire circumstances. Neither the regime nor the US could be confident in how many such ICBMs might detonate over their targets, but that might not matter for a regime facing extreme danger—and that might provide cold comfort for the US if even one or two ICBM strikes succeed. The DPRK is highly likely to see this as having significant military utility.
  • Deterrence:[8] This capability for use means that the US must take into account the possibility of being struck by nuclear-armed ICBMs. History suggests that the possibility of incurring nuclear strikes has an inhibiting effect in countries’ calculations. North Korea, which for some 65 years has had to try to deter without any nuclear capability against the US homeland, almost certainly perceives even a limited such capability as worthwhile.
  • Prestige: Kim Jong Un has repeatedly indicated that he views the ICBM program as a source of domestic and international prestige. The North probably has already obtained much of the prestige it can gain from its ICBM force via successful flight tests, exposures to the media, and indications of deployment. Further bolstering the reliability of the ICBM force probably would not add that much more.
  • Diplomacy: North Korea almost certainly views a deployed ICBM force as a fait accompli bolstering its claim for recognition as a “nuclear power,” raising the price it can charge in talks with the US, and increasing the attractiveness to Washington of partial solutions (e.g., ICBM testing or deployment freezes) that would leave the North possessing some nuclear weapons. An ICBM threat to the US homeland also raises Japanese and South Korean concerns about US extended deterrence that North Korea probably relishes being able to exploit.[9]
  • A Basis for Further Flight Testing: The DPRK still can improve ICBM reliability at any time by resuming flight tests, whether by breaking a unilateral pledge or breaking out of any future agreement. The North also can manipulate the threat of resuming or the resumption of flight tests for political purposes, as it has often done in the past (and did again on July 16, 2019).

The Value of Preventing Further Flight Testing

A halt to further ICBM flight tests has considerable security value for the US, even if North Korea has deployed ICBMs based only on a few flight tests. First and foremost, it would presumably reduce the likelihood of ICBM use against the US. The DPRK almost certainly understands that its current ICBM force is not as reliable/effective as it would be if at least a few more flight tests were conducted. Having an ICBM force of its current reliability presumably would incline the DPRK to limit the kinds of provocations and non-retaliatory military operations it chose to initiate compared to having a much more reliable ICBM force.[10]

The consequences of ICBM use against the US would also be reduced. If the DPRK did launch its current ICBMs, probably fewer than half would reach the United States. This, in turn, would reduce the number of warheads that would come within range of US missile defenses, increasing the defense’s likely success despite the limit to its effectiveness.[11] In addition, some warheads that made it through the boost phase and US missile defenses probably would not detonate—a proportion that would likely be higher given the North’s limited full-range ICBM testing and nuclear testing to date. Clearly, more DPRK ICBM warheads would be likely to reach US targets and detonate if ICBM testing resumed (and presumably even more if nuclear testing also resumed).

Finally, a lack of flight testing will probably prevent the DPRK from improving current ICBM reliability appreciably over time. (We do not know the North’s own assessment on this.) The North can, however, use three broad methods other than flight testing to contribute substantially to maintaining the current level of reliability, or at least in slowing degradation:

  • Static Rocket Testing: Running rocket engines in ground-based test stands contributes importantly to development and successful series production—and in promoting smooth engine operation, a major contributor to ICBM reliability. Static tests would be critical in maintaining reliability, but would not provide a complete solution given the differences from actual flight conditions and the contribution of other ICBM subsystems to overall system reliability.
  • Other Non-Flight Testing: Some limitations of static testing can be addressed by operating other ICBM subsystems (such as guidance and thrust vector control) using simulated inputs from other portions of the ICBM. Even entire ICBMs can undergo such “hardware-in-the-loop” tests. Key ICBM subsystems and components also can be tested in ground facilities that try to duplicate the kinds of temperatures and vibrations they would experience in flight (“shake and bake”). We do not know how many such test capabilities the DPRK has, or how good they are. Regardless, these methods still leave considerable gaps in assessing the full-up ICBM system over the entire regime of operational use.
  • Computer Simulation: Using computers to run ICBM system software under various circumstances, test hardware/software interfaces and test interactions between different missile subsystems all can help, along with the other two methods, to maintain the reliability of an ICBM. It is unclear how capable North Korea is in this area, but its efforts would be significantly limited by the relatively small number of real-world missile tests it has conducted, which provide the underlying basis for effective computer simulations. (North Korea has conducted some 120 of these tests compared to many hundreds for the US or Russia.[12])

The Bottom Line

It is credible that North Korea would deploy nuclear-armed ICBMs based on the current amount of flight testing. Although such missiles are almost certainly not highly reliable, the DPRK (based on North Korean standards) probably regards them as sufficiently reliable for their current purposes. Preventing further flight tests has considerable security value for the US, even if it has not prevented North Korea from deploying ICBMs, in part because it will probably prevent the DPRK from improving current ICBM reliability appreciably over time.

  1. [1]

    This is bolstered by other statements in Kim Jong Un’s 2018 New Year’s Address: “An outstanding success our Party, state and people won last year was the accomplishment of the great, historic cause of perfecting the national nuclear forces. On this platform one year ago I officially made public on behalf of the Party and government that we had entered the final stage of preparation for the test launch of an intercontinental ballistic missile. In the past one year we conducted several rounds of its test launch, aimed at implementing the programme, safely and transparently, thus proving before the eyes of the world its definite success. By also conducting tests of various means of nuclear delivery and super-intense thermonuclear weapon, we attained our general orientation and strategic goal with success, and our Republic has at last come to possess a powerful and reliable war deterrent, which no force and nothing can reverse.”

  2. [2]

    The flight test information in this paragraph is drawn from: James Martin Center for Nonproliferation Studies, “The CNS North Korea Missile Test Database,” Nuclear Threat Initiative, last updated May 14, 2019,

  3. [3]

    Joseph Bermudez, Victor Cha and Lisa Collins, “Undeclared North Korea: The Sangnam-ni Missile Operating Base,” Center for Strategic and International Studies Beyond Parallel, February 15, 2019,; and John Schilling and Henry Kan, “The Future of North Korean Nuclear Delivery Systems,” North Korea’s Nuclear Future Series, US-Korea Institute at SAIS, April 2015, 17,

  4. [4]

    Michael Elleman, “Why a Formal End to North Korean Missile Testing Makes Sense,” 38 North, February 26, 2019,

  5. [5]


  6. [6]


  7. [7]

    Michael Elleman, “The Pukguksong-2: Lowering the Bar on Combat Readiness?” 38 North, May 25, 2017,

  8. [8]

    John Schilling, “North Korea Finally Tests an ICBM,” 38 North, July 5, 2017,; and Schilling and Kan, The Future of North Korean Nuclear Delivery Systems, 22.

  9. [9]

    Schilling, “North Korea Finally Tests an ICBM.”

  10. [10]

    Elleman, “The Pukguksong-2: Lowering the Bar on Combat Readiness?”

  11. [11]

    Michael Elleman, “Why a Formal End to North Korean Missile Testing Makes Sense.”

  12. [12]

    James Martin Center for Nonproliferation Studies, “The CNS North Korea Missile Test Database.”

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