Perspecti ve
Expert insights on a timely policy issue
C O R P O R AT I O N
New Challenges in Cross-Domain Deterrence
King Mallory
A
fter a period of U.S. primacy that followed the end of
the Cold War, the United States has been confronted
with successful actions on the part of Russia and China
to revise the territorial status quo in Ukraine and the
West Pacic. Both countries employed “gray zone” or “hybrid war-
fare” tactics in pursuing these goals. After its 2001 and 2003 inva-
sions of Afghanistan and Iraq, the United States was challenged by
a signicant increase in activity on the part of transnational groups
of nonstate actors employing terrorist tactics of warfare as well. e
cumulative activities of all of these actors have cast in doubt the
territorial status quo in Europe, the Middle East, North and sub-
Saharan Africa, and South and East Asia.
All sets of actors have employed asymmetric military tactics.
ese tactics have been designed to avoid direct conventional
military confrontation with the United States in areas of warfare in
which the United States dominates and has superior power projec-
tion capabilities.
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ese developments have unsettled traditional
U.S. allies in Europe, Asia, and the Middle East and North Africa
that have long relied on the Pax Americana—extended American
deterrence of aggression against them—to guarantee both national
and regional security.
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At the same time that the use of hybrid and terrorist tactics
of warfare has gained newfound salience in the land domain of
warfare, the probability that future military conict will encompass
conict in space and cyberspace has risen signicantly. Not only
has the United States’ ability to deter aggression in the traditional
air, land, and sea domains of warfare been cast in doubt, but new
requirements to deter future aggression in the domains of space and
cyberspace have also arisen. When an opponent has no incentive
to initiate or escalate conict at any given intervention or escala-
tion threshold in any given domain of warfare—both vertically
and horizontally within that domain and laterally into one or more
additional domains of warfare—successful cross-domain deterrence
can be said to be in eect.
is Perspective examines ways and means by which the
United States and its allies might meet these new challenges in
