Guam, the small island territory in the Pacific Ocean, plays a unique strategic role in the United States’ Indo-Pacific strategy. In a new article, part of a Hudson Institute collection of essays on the challenges and motivations of defending Guam, Center Fellow Oriana Skylar Mastro analyzes the island’s strategic importance to the United States, China’s threats to U.S. forces on the island, and the pathways to deterrence against Chinese encroachment in the region. 

Mastro enumerates a number of reasons behind Guam’s strategic importance. First, “the Chinese missile threat to U.S. regional bases, especially those located in the first island chain, enhances the operational role of those bases sufficiently distant from China to partially mitigate the threat it poses, yet also close enough to be operationally impactful.” Guam’s geostrategic potential is rooted in its proximity to China, and represents “the westernmost location from which the U.S. can project power, manage logistics, and establish command and control.” 

In a Taiwan contingency, Mastro argues that Guam would play an important role as a logistics hub and jumping-off point for combat forces headed toward the Taiwan Strait, with the caveat that U.S. forces could maintain roughly half the sortie rate from Guam as that from Kadena Air Base in Okinawa, Japan. Another reason behind Guam’s strategic utility comes from reliable base access, which is more reliable than in other Asian host countries.

Despite the U.S. force posture and the island’s protective distance from China, Guam remains vulnerable to Chinese intermediate-range ballistic missile attack. According to Mastro, the U.S. has systems on the island to protect against missile threats, such as a THAAD battery, but “U.S. military commanders want much more of a guarantee that the U.S. would be able to continue operations out of Guam even under Chinese missile attack.”

Given China’s ability to threaten U.S. bases on the island, Mastro proposes an “unappreciated and underutilized” pathway to deterrence: deterrence by resiliency. Similar to deterrence by punishment, which seeks to prevent adversary attacks by employing the threat of severe penalties should the adversary do so, deterrence by resiliency is based primarily on shaping adversaries’ perceptions of one’s own capabilities. “However, unlike deterrence by punishment, the goal is not to create fear of retaliation but rather to encourage the perception that disruptive events would have little effect on an adversary.” Mastro uses the term resiliency to refer to a state’s ability to both absorb and deflect costs at a given level of violence.

Mastro argues that resilience is about signaling to China that “the benefits it would derive from a particular action would actually be less than it believes them to be. Improving defenses can enhance deterrence through this mechanism, but, given its limitations, other avenues—in particular, pursuing viable alternatives and creating redundancy—should also be pursued to ensure that an attack on Guam would not cripple a U.S. war effort.”

Guam, frequently cited as the U.S.’s viable alternative to bases within the first island chain, represents a critical strategic waypoint, but as long as the U.S. is reliant on the island to fight and win a war, “China will ensure that it can effectively target the island, thus making messaging associated with Guam’s defense key.” Mastro proposes that the language about defending Guam must expand to accomodate resilience contingencies for the island’s planned defenses, which, “once in place and even under attack […] would ensure that the US could continue operations there to the degree necessary to, for example, maintain air superiority over the Taiwan Strait.” 

Whether China would accept deterrence by resilience remains to be seen, but policymakers must employ new thinking about Guam’s defense to meet the new security challenges posed by China.