Jeffrey LewisActon on CPGS

James Acton has published an excellent new monograph on Conventional Prompt Global Strike, entitled Silver Bullet? Asking the Right Questions About Conventional Prompt Global Strike.

You can watch or listen to James present the report.

Like everything James writes, it is careful and nonpolemical. That always makes the competing headlines fun.

Elaine Grossman went with “Global-Strike Arms Pose Little-Recognized Stability Risks: Report“; The Washington Free Beacon, on the other hand, went with “Expert: ‘Conventional Prompt Global Strike System’ Could Deter China.”  The poor folks at National Defense just seemed plain confused.  They went with the vague: “Report: Conventional Prompt Global Strike Weapons Face Challenges.”

Challenges indeed. It would probably be best if you just read it yourself!


  1. j_kies (History)

    Huge kudos to the arms control community for doing a throughly researched backgrounder for policy makers and those who advise them. By diligently framing it as a series of questions that should be asked and putting the open source material in context this is especially useful.

    As a comment, its important to acknowledge the discussions have to do with the weapon, not with the means to aim it and sustain it that would be a weapon system.

  2. George William Herbert (History)

    I believe I have said this before, but relevant to this…

    My company bid on a small launch vehicle for the FALCON small launch vehicle component, which was intended as a space launch vehicle but inherently and explicitly coupled to the conventional ICBM (either ballistic, or boost-glide booster) role. We did not get a phase 1 contract.

    Our proposal specifically increased the payload capability enough to meet the payload specification in the CICBM role fired south, the long way more or less over the South Pole, rather than north, for trajectories to NK or Iran. I did this because it cost only a small amount to make the booster bigger, and because I could not imagine a use scenario where it would be safe to fire over or near Russia to get to Iran or NK. Apparently the other bidders didn’t, and I was quietly informed I had overreached in overspecifying.

    • Jonah Speaks (History)

      Inspired concept, George. Other things equal, it is preferable that missiles aimed at others not overfly Russia, lest the Russians get confused and think they are under attack.

      For targets in North Korea, Iran, or China, how much more expensive would it be to have missiles that could fire either north or south, instead of north only? How much longer would it take to fly to these targets by firing south rather than north? What countries would be overflown instead of Russia?

      Can Russian radars distinguish trajectories of northern missiles that have Russian targets from missiles that are overflying Russia, but not hitting Russia? Can Russian radars distinguish trajectories of southern missiles that have Russian targets from missiles that are flying in Russia’s direction, but hitting short of Russia?

      It is not entirely obvious that a U.S. President would refuse to launch missiles that overfly Russia, if a bad situation appeared to demand it. We would expect the Russians would already know (diplomatically, through intelligence, and by common sense) who we are aiming at, even if they could not absolutely verify it before the missiles landed. Building in the option of a second direction makes sense, if it reduces the risk of confusing Russia.

    • George William Herbert (History)

      Without making ITAR people jump up and down in panic, let’s say in round numbers it’s 15% bigger on the ground, and somewhat less than 15% more expensive (8%?).

      In terms of time, it’s *roughly* about 2/3 of a low earth orbit (60 min) instead of 1/3 (30 min) to go around the long way.

      I did not specifically analyze the Russian OTH radar situation for what they would see for southern trajectories. That would be useful at some point, don’t have time this week.

      For northern trajectories, I certainly hope they would be able to tell ballistic weapons were going over them not down onto them… If you can’t do that, you can’t tell where it’s going to land along its flightpath at all.

      For skip / hypersonic glide trajectories, target point could be anywhere along the flight line (it takes a bit of time to start diving, but you can’t tell ahead of time when it’s going to start that terminal dive). So having it overfly and watching to see if it starts to dive, as it passes over your territory, would be unpleasant.

    • Jonah Speaks (History)

      Thanks, George.

      Expense: If the option to fly south is only 8% extra, it is cheap relative to the overall military budget. Nuclear weapons cost maybe 1% of the budget, ICBMs less than one-third of that, so 8% of that is less than one dollar out of $3,750 military dollars. Since the nuclear component is the most dangerous part of the arsenal, any measure that reduces the odds of an unintended nuclear war, even by a small amount, could easily justify this extra cost.

      Timing: At first, 60 minutes versus 30 minutes sounds like an eternity, but then I thought, we now have the Internet. Land-based missiles are no longer useful for first strike, because the element of surprise is lost. (This just in from the Internet: Hundreds of land-based missiles have just left their silos… Look at these pictures!) The only plausible first-strike nuke must come from a submarine. Since the land-based nukes are only useful for second strike, an extra 30 minutes to get where they are going makes no difference. The enemy already knows they are coming.

      Radars: Good to know that Russian radars can probably distinguish missiles aimed at Russia from missiles going elsewhere. If the U.S. decides to develop missiles that can fly south, I am sure the Russians will beef up their southern radars as needed.

      Finally, kudos to Acton for a well-researched and lengthy tome on CPGS. He mentions three ambiguities: “warhead ambiguity” – there is no technical reason why these hypersonic vehicles could not carry nuclear warheads. “target ambiguity” – an enemy cannot be sure if we are targeting conventional or nuclear assets.

      Finally, there is “destination ambiguity” – uncertaintly about which country a weapon is aimed at. Acton writes, “Destination ambiguity… appears liable to increase the probability that Russia or China could wrongly conclude that a CPGS weapon were heading for their territory. In this scenario, if Moscow or Beijing misidentified the CPGS weapon as a nuclear weapon … they might launch a nuclear response.” (p. 118) If THAT were to happen, the results could be worse than “unpleasant”.

  3. bob (History)

    ‘Silver Bullet’ – sounds like a great name for the skip/glide project, oh yeah, teen werewolves are so overdone.

    Mmmmm, how about ‘Silver Bird’ then?

    Waddaya mean its taken!