This document summarizes key points from a seminar on space and cyber deterrence. It notes that developing offensive space and cyber capabilities poses risks of strategic instability, as relatively low-cost attacks could severely damage an adversary. Once these thresholds are crossed, rapid escalation is possible given the ephemeral nature of cyberweapons and uncertainty of impacts. Maintaining resilience is important but adversaries will seek countermeasures. Extended deterrence through alliances could help deter attacks on space systems that serve both military and commercial customers. However, assuring a second-strike capability in space, like submarine-launched ballistic missiles provide for nuclear deterrence, remains challenging without a clear analogue. Overall uncertainty regarding capabilities and effects in these domains complicates deter

1. Space and Cyber: Roles
and Issues in Deterrence
Cross-Domain Deterrence Seminar
Lawrence Livermore National Laboratory
Livermore, California
November 18, 2014
Bruce W. MacDonald
United States Institute of Peace
Johns Hopkins University,
School of Advanced International Studies

2. 2
Serious Risks of Future
Space/Cyber Instability
Technical challenge/cost for China and Russia to
develop credible space offense/cyber attack capa-
bilities are reasonable for military benefits provided
There is thus an inherent risk of strategic instability
when relatively modest defense investments can
create disproportionate danger to an adversary
For peer/near-peer powers, a disabling space/cyber
first strike against an adversary seems far preferable
to, and easier to execute than, retaliating
This is the essence of crisis instability, when pre-
empting pays far greater benefits than retaliating
Future depends on how architectures and
perceptions will shape the strategic landscape

3. Space/Cyber Domains Different, Less
Predictable Than Nuclear/Conventional
Monitoring adversary capabilities and damage
assessment much more difficult, especially for cyber
Capability costs are modest for potential benefits, <<
nuclear/conventional costs
Larger the scope of use, larger the uncertainty of
impact level, given levels of interconnection
For space, no equivalent to SSBN/SLBM force to
provide assured retaliation; cyber situation more
mixed but hardly reassuring
Strategic level attacks potentially devastating but
limited attacks often tactically useful
3

4. Escalation
At tactical level, very easy to breach threshold into space
and cyber use
– Often tactically useful, EW/jamming precedents, “bloodless”
For near future, other than as a signaling device, not
much to be gained from gradual escalation in space or
cyber in a deep crisis
Once an uncertain threshold breached, potential is great
for rapid escalation, especially if breach substantial
– Ephemeral nature of cyberweapons, gives adversary less time to
button up/retaliate, inexperience w/space-cyber conflict
A de minimis threshold below which escalation risks are
minimal? How far can one go before instability occurs?
Major strategic/economic attacks very risky, likely to lead
to all-out strategic conflict, even if non-nuclear
Tactical use of space/cyber has long history, could be a
“gateway drug” to escalation, even strategic use
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5. 5
Uncertainty and Risk Aversion
Hard to know adversary weaponry numbers or capability
Space and cyber experiencing rapid technological
change; in cyber, architectures/software constantly
changing, so weapon effectiveness changing as well
Advanced country cross-domain interconnectedness
growing exponentially, so even more effects uncertainty
U.S. alliances add a major caution to our adversaries
Worst case assessments of crippling capabilities could
be self-deterring, hence …
Possible firebreak: Risk Aversion
– Attacker uncertain of both attack effectiveness, adversary
retaliation, and vice versa
– “Hysteresis effect” may provide limited stability in a crisis, help
discourage significant first use, and escalation in conflict
– Effect probably becomes more pronounced the more “strategic”
the level of attack considered

7. Can Deterrence/Hysteresis Last Until
Space/Cyber Resilience Is Achieved?
Impact of hysteresis likely becomes more pronounced
the more “strategic” the level of attack being considered
What are key thresholds? Are they robust?
– Any use of space/cyber offense No
– Isolated use No
– Tactical use Likely No
– Regional use Maybe
– Strategic use Probably Yes
Resilience is great space/cyber goal, but no silver bullet
Is it achievable? If achieved, can it be maintained?
Adversaries will seek countermeasures, as we likely would
against, e.g., Chinese/Russian resiliency measures
Measure/countermeasure competition seems likely
If resilience is too effective, would there be “moral
hazard” problems, i.e., becomes easier to escalate? 7

8. Contact Information
Bruce W. MacDonald
Adjunct Professor, Johns Hopkins University/SAIS
Special Advisor
Arms Control and Nonproliferation Project
United States Institute of Peace
2301 Constitution Avenue, NW
Washington, D.C. 20036
(202) 429-3832
bmacdonald@usip.org
Adjunct Professor
Johns Hopkins University
School of Advanced International Studies

9. 9
Space Deterrence and Extended Deterrence
Collateral effects are a serious drawback when targeted
space assets also serve commercial customers
– Will carriers hesitate to provide services in conflict?
But mixing military and commercial, U.S. and friendly
foreign, payloads probably strengthens space deterrence
– Other countries have greater stake in space stability, raises the
price for adversaries (and U.S.) to initiate space attacks
Extended deterrence operates in space and cyber
domains: explicit alliance security guarantees raise
stakes of attacking any alliance member
Probably a lower threshold to this effect – but where is it?
For a change, extended deterrence appears to be more
of a two-way street in space, with allies making a
concrete contribution: attacking mixed use space assets
is an attack on all the users of the assets, not just U.S.

10. Challenge to Space Stability:
No Clear SLBM Analogue
Most stabilizing aspect of strategic nuclear balance is the
SSBN/SLBM element – assures devastating 2nd strike: is a
secure second strike OCS capability possible?
Invisible Arsenals – Space, and especially cyber, are
“murky to invisible”
Worst case capability assessments could be self-deterring
Also, arsenal effectiveness has lower confidence from
dynamic technological environment, especially for cyber
Highly uncertain collateral/unintended effects of
countervalue space/cyber attacks also could be self-
deterring – like virulent bioweapons
But how do you deter without making public your
capabilities? 10