by Jasmine Moheb
Staff Writer

In the fifth century B.C.-as the Peloponnesian War determined the fate of the Greek islands-one of the world’s greatest historians, Thucydides, wrote a book that modern security originates from. The type of warfare utilized, however, would only be defined 26 centuries later.


Erik Gartzke, a Professor at the University of California-San Diego and founder of the University’s Center for Peace and Security Studies, describes the central point of his group’s research, which no intellectual literature has broken down to a science before: cross-domain deterrence. Gartzke clarifies that the concept of deterrence has “been practiced since the beginning of time… [but] there wasn’t an articulated theoretical understanding” of it until the rise of nuclear weapons. He defines classic deterrence as essentially trying to prevent someone from doing something you don’t want them to do. With nuclear deterrence, countries protect themselves by threatening to retaliate if their adversary attacks them. This is meant to render the original attack so costly that it encourages the opponent not to do it in the first place.

Cross-domain deterrence takes the notion of typical deterrence one step further and is defined as “trying to deter somebody with unlike means.” This idea is especially applicable today in the Pentagon’s five outlined domains: land, sea, cyber, air, and space — all areas of potential conflict or deterrence. To truly understand how cross-domain differs from classic deterrence, Gartzke describes the Peloponnesian War as an introductory example. In Greece, Athens was the strongest naval power while Sparta was the strongest land power, and as each dominated different domains of the war, neither was able to fully overpower the other. Deterrence exists in this instance as the Athenian navy is deterred by the strength of the Spartan army, and vice versa – making it cross-domain. This occurred once again in the 19th century Napoleonic Wars when the British had the best navy in the world but the French had a stronger army on land. When Napoleon conquered Egypt, prohibiting the British from getting to their colony of India, the British sent their navy to defeat Napoleon’s army. The concept of deterrence is introduced when we ask if the French would have avoided conflict, had they suspected that the British army would have been able to overpower them.

Cross-domain deterrence is especially applicable in the 21st century as military capabilities have expanded to an unprecedented diversity of domains. With the rise of cybersecurity and space command operations, the discretion of military affairs has only increased, and with it, new challenges have arisen. Gartzke describes nuclear weapons-in the classic framework of deterrence-as being obvious and intentionally visible to an adversary to prove the strength of a nation. However, the transparent nature of deterrence has changed as weapons developments in the modern era include discrete capabilities. This was exemplified recently when the United States was contesting Chinese domination of sea and air space, and contemplated sending a threatening message by flying their best aircraft into the East China Sea: the B-2 Bomber – a stealth bomber that is meant to fly unseen. However, due to its invisible nature, the only way to noticeably intimidate the Chinese would be to fly a weaker aircraft that was older and more visible, the B-52 – “[which] has the virtue that it’s obvious…you can’t hide it, and that’s the point of [proving your presence in strength].” In a larger context, this example proves how, as military technology becomes more discrete and efficient, it is difficult to deter the adversary by displaying your best assets, thereby diminishing the potential for maximum deterrence.

B2 Stealth Bomber

Another problem that arises with deterrence, and especially cross-domain deterrence, is the potential for escalation, as Gartzke explains, “the same mechanisms that are said to lead to escalation are also said to lead to the prevention of escalation [or] deterrence.” This is explained by Gartzke in the context of relationships among countries that could be stabilizing or destabilizing to a framework of peace and stability in the global sphere. He cites Robert Jervis’s “Spiral Model” which occurs when “[a country does] something provocative and an adversary reacts to that by being more provocative so [the original actor does] something more provocative and it spirals out of control.” This is especially relevant in the 21st century as a greater range of warfare enters unknown territory in terms of potential escalating action that could push the intent of deterrence into conflict.

In a recent case between Pakistan and India, an initial strike by Pakistan caused retaliation by the Indian government, deterring further Pakistani aggression to the Indian state. This was the case of a stabilizing relationship. However, an example of a destabilizing relationship occurred in 2007 when the Chinese developed an anti-satellite missile, testing it against one of their own old satellites, which they successfully destroyed in outer space. While they intended this to be a signal that the United States needed to decrease its presence in the space domain due to China’s increasing dominance in the sector, the message was perceived much more aggressively by Washington. This was because the new Chinese potential to shoot down U.S. satellites could undermine a major domain the United States relies on for intelligence networks. The U.S. response to China-rather than resulting in surrender-increased aggression and escalated tension amongst the two countries, producing a destabilizing relationship. Gartzke claims that while cross-domain deterrence and the increase of modern-day capabilities can “multiply the forms of existing deterrence, they can also multiply the number of ways in which aggressive actions can spiral and escalate aggression.”

In a final insight, Gartzke describes the macro perspective of the world, stating how important it is for the United States to be open to change, especially at the level of international organizations with major powers such as Russia and China. Active compromise with these nations yields stabilizing action that can heed better relations in the future. He relays a message to students interested in security policy to take actions that will bring stability to the world and, given the advancing possibilities of deterrence, rethink “if it’s necessary to wield power or if you can get it through other forms of peaceful influence.”

Professor Gartzke and Jon Lindsay’s book on “Cross-Domain Deterrence” can be purchased starting March 1, 2019 and further information can be found through UC San Diego at

Photos by:
Brian Wilson
U.S. Air Force

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