From Saigon to the Pentagon: Hung Cao’s Journey and the Transformation of Pacific Defense
We had the opportunity to sit down with the Under Secretary of the Navy earlier this week in his office to discuss his recent visit to Vietnam with the Secretary of War as well as his focus on the Guam defense challenge.
On October 3, 2025, Hung Cao was sworn in as Under Secretary of the Navy. Very soon thereafter, on October 21, 2025, he visited Guam in his capacity as the Senior Defense Official for Guam and the Commonwealth of the Northern Mariana Islands, signaling the urgency and priority the island has as a critical hub of American power projection.
Cao’s connection to the region runs far deeper than his official portfolio. Fifty years ago, as a four-year-old refugee fleeing the fall of Saigon in 1975, he was processed on Guam before entering the United States. His return to Vietnam alongside Secretary of War Pete Hegseth on November 2, 2025, represents not merely a diplomatic mission, but a profound full-circle moment in American-Vietnamese relations and a symbol of the broader transformation reshaping Pacific security dynamics.
The Personal and the Strategic Converge
Hung Cao’s biography embodies the complex interweaving of American immigration history with contemporary defense policy. Born in Vietnam, he fled the country as a child refugee during the fall of Saigon in 1975 and arrived in the United States, starting a new life which has shaped his perspectives and career. His journey from Vietnamese refugee to Navy Captain to senior Pentagon official represents a uniquely American narrative, but one that carries particular resonance in the current geopolitical moment.
Before his appointment as Under Secretary, Cao had a distinguished military career serving in special operations as a Navy Deep Sea Diver and Explosive Ordnance Disposal officer, including deployments to Iraq, Afghanistan, and Somalia. He is known for his leadership in high-risk environments and for taking a practical, safety-focused approach to missions. Former colleagues respected his judgment and his concern for the well-being of his subordinates in combat situations. He retired from active duty at the rank of Captain.
For Vietnam generation Americans, Cao’s ascent to this position carries profound symbolic weight. The fact that a senior U.S. defense official of Vietnamese origin is now helping to shape the bilateral security relationship represents a genuine end to one era and the beginning of another. As a Vietnamese American who has become one of the most prominent Asian Americans to achieve a senior civilian post in the Department of the Navy, his presence in Hanoi alongside Secretary Hegseth was warmly received by Vietnamese officials, a reception that would have been unimaginable just a few decades ago and remains remarkable even today. The war that divided both nations for so long has given way to a pragmatic partnership built on shared interests and mutual concerns about regional stability.
Maritime Security: The New Foundation of U.S.-Vietnam Relations
The central focus of Cao’s work in Vietnam centers on maritime security, safety, and the joint commitment both nations share to maintaining an open and free Pacific. This is not abstract diplomacy. Vietnam, like the Philippines, has experienced repeated aggressive actions by Chinese maritime forces against civilian vessels, including fishing boats and other commercial craft operating in waters Vietnam considers within its legitimate maritime zone.
Chinese government vessels, including law enforcement and maritime militia, have regularly attacked and harassed Vietnamese fishing vessels in the South China Sea, particularly near the disputed Paracel and Spratly Islands. Documented incidents include beatings of crew members, use of iron bars and water cannons, ramming and sinking of vessels, confiscation of fishing equipment and catches, and even detainment of fishermen.
These acts have led to international protests by Vietnam, injury and financial loss among Vietnamese fishermen, and serve as part of China’s broader effort to assert its maritime claims in the South China Sea in disregard of internationally recognized Exclusive Economic Zones. This pattern of aggression has created genuine alarm in Hanoi and has driven Vietnamese interest in enhancing their capacity to monitor, patrol, and defend their maritime approaches.
The United States has responded to these concerns through concrete capability transfers. Over the past several years, Washington has transferred three Hamilton-class cutters from the U.S. Coast Guard to the Vietnamese Coast Guard. These vessels, decommissioned as the Coast Guard transitions to its new National Security Cutters, have been refurbished before transfer to ensure they remain operationally effective.
By enhancing Vietnamese maritime domain awareness and patrol capability, the United States strengthens the collective capacity of regional states to resist coercion and maintain the freedom of navigation that benefits all Pacific nations. Cao emphasized that this cooperation represents the core of what Vietnam and the United States are working toward together: both nations, as Pacific powers, share a fundamental interest in keeping the Pacific open and free for commercial shipping, trade, and peaceful economic activity.
It is important to understand that Vietnam’s deepening security cooperation with the United States operates within carefully defined parameters. Vietnamese leadership has articulated four key limitations in its allied engagement policy, commonly referred to as the Four Nos. These form the foundation of Vietnam’s defense and foreign policy strategy, aiming to maintain autonomy and strategic balance amid major power competition, especially between the United States and China.
The Four Nos policy includes these principles: no participation in military alliances; no aligning with one country to oppose another; no foreign military bases in Vietnamese territory or use of its territory to counter other countries; and no use of force or threat to use force in international relations. Vietnamese officials regularly reaffirm their commitment to these principles, both in regional forums such as the Shangri-La Dialogue and within their defense white papers. This policy is sometimes also termed bamboo diplomacy, reflecting the flexible yet resilient balancing act Vietnam maintains amidst major power rivalry.
As Vietnam has deepened relations with the United States, European Union, Japan, and Australia, as well as continued pragmatic relations with China and Russia, the Four Nos remain central. The Hamilton-class transfers are emblematic of a broader approach that sees capability building in partner nations as force multiplication for American interests, respecting Vietnam’s need for autonomy while addressing shared security concerns.
Guam: From Strategic Triangle to Distributed Hub
When our book Rebuilding American Military Power in the Pacific: A 21st Century Strategy was published in 2013, it included graphics illustrating what we called a strategic triangle and a strategic quadrangle. The strategic triangle identified Hawaii, Guam, and Japan as the three foundational bases from which the United States projected military power throughout the Pacific. The strategic quadrangle expanded this framework to include Australia and South Korea, with the maritime and aerial domains serving as the connective tissue enabling power projection across this vast geography. The strategic quadrangle was conceptualized as the area from Japan to South Korea, to Singapore to Australia and identified as the engagement zone.
If those graphics were redrawn today, they would look fundamentally different. The transformation reflects not a diminution of these locations’ importance but rather an evolution in how American military power operates in the twenty-first century. Guam and the surrounding areas have become increasingly correlated with the broader shift toward distributed maritime operations, agile combat employment, and the Marine Corps’ emphasis on Expeditionary Advanced Base Operations. Rather than serving primarily as a fixed base from which forces deploy, Guam is increasingly conceptualized as a node in a distributed network, a place from which capabilities can be rapidly dispersed throughout the region in response to specific crises or contingencies.
This shift reflects hard-learned lessons from decades of defense analysis. Concentration of forces and capabilities creates vulnerability, particularly in an era of precision strike and advanced targeting. By distributing capabilities across a wider geographic area, by emphasizing mobility and rapid repositioning, and by building the infrastructure to support dispersed operations, the United States makes itself a more difficult target while simultaneously enhancing its ability to respond flexibly to emerging challenges.
Cao explained that the goal extends beyond Guam itself to encompass the broader Mariana Islands, which would significantly expand the area available for supporting what he describes as a hub for force protection and force projection or, alternatively, as a distributed engagement zone. Adding the Northern Mariana Islands to Guam for U.S. military operational purposes increases the total land area by more than 80 percent. Guam itself has a land area of approximately 212 square miles, while the Northern Mariana Islands, which include Saipan, Tinian, Rota, and other islands, have a collective land area of about 179 square miles.
This expanded operational space provides multiple advantages: it complicates adversary targeting, creates redundancy in critical capabilities, enables forces to operate from unexpected vectors, and provides depth for logistics and sustainment operations.
Guam sits at the center of this transformation, not as a single target but as a coordinating hub within a broader distributed network. Its substantial infrastructure, strategic location, and established logistics capabilities make it invaluable for supporting distributed operations throughout the region. But its value comes not from concentrating everything in one place but from enabling operations everywhere else.
The transformation of Guam’s role and the deepening of U.S.-Vietnam maritime cooperation are not isolated developments but parts of a broader reconfiguration of Pacific security architecture. The visits Cao has made to Guam and Vietnam in his first weeks in office reinforce U.S. capabilities throughout the region to address security and defense challenges. More importantly, they demonstrate a clear commitment to working with allies and partners as the foundation of American strategy.
This alliance-centric approach reflects a fundamental reality: the United States cannot unilaterally ensure Pacific security. The region is too vast, the challenges too diverse, and the resources required too substantial for any single nation to manage alone. But the United States does not operate alone. It benefits from an unmatched network of allies and partners, many of whom share American concerns about coercion, aggression, and the erosion of the rules-based international order.
Vietnam’s evolution from adversary to partner represents one of the more remarkable transformations in this alliance network. The relationship remains carefully calibrated, with both sides conscious of historical sensitivities and domestic political considerations. But the trajectory is unmistakable. Shared concerns about Chinese maritime behavior, mutual interest in free trade and open sea lanes, and complementary strategic perspectives have created genuine common ground. The United States gains a partner with local knowledge, geographic proximity, and legitimate regional standing. Vietnam gains access to advanced capabilities, operational experience, and the implicit deterrent value of American partnership.
This pattern repeats throughout the region. The Philippines, after a period of strained relations, has reinvigorated its alliance with the United States, granting access to additional bases and expanding defense cooperation. Australia has committed to unprecedented defense integration, including hosting U.S. rotational forces and cooperating on advanced capabilities. Japan continues to expand its defense capabilities and operational cooperation with American forces. South Korea, despite periodic friction over burden-sharing, maintains its fundamental alliance commitment.
The strategic quadrangle of the 2013 analysis has become something more complex and more resilient: a network of overlapping partnerships, each calibrated to specific circumstances but collectively creating a web of relationships that enhances regional stability. This network does not depend on any single node; it distributes both capability and strategic commitment across multiple nations and locations.
The Symbolic and the Strategic
Hung Cao’s rapid engagement with Guam and Vietnam in his first weeks as Under Secretary illustrates the integration of symbolic and strategic dimensions in contemporary defense policy. His personal story resonates throughout the region, particularly in Vietnam, where his presence communicates respect, partnership, and the possibility of transformation. But symbolism alone accomplishes nothing without substantive policy to back it. The Coast Guard cutter transfers, the expansion of operational space in the Marianas, the emphasis on distributed operations, these are concrete expressions of strategic commitment.
The transformation of U.S. policy in the Pacific reflects the region’s changing dynamics. The comfortable American dominance of the post-Cold War era has given way to genuine strategic competition. China’s rise, however one evaluates its ultimate trajectory, has created new challenges that demand new responses. The distributed operational concepts, the emphasis on alliance capability building, the focus on presence and engagement rather than episodic intervention, all represent adaptations to this changed environment.
For those who remember the fall of Saigon in 1975, Hung Cao’s presence in Hanoi fifty years later as a senior American defense official cannot help but prompt reflection on how profoundly the world has changed. The transformation of U.S.-Vietnam relations from bitter conflict to security partnership represents one of the more remarkable shifts in modern international relations. That this partnership now focuses on maritime security and resistance to coercion adds another layer of historical irony and strategic logic.
The Pacific remains what it has always been: vast, diverse, economically vital, and strategically crucial. How the United States engages with this region will shape global security for decades to come. Under Secretary Hung Cao’s early emphasis on Guam and Vietnam signals that this engagement will be grounded in both strategic realism and an appreciation for the region’s complexity. His personal journey from refugee to defense leader adds a human dimension to these strategic imperatives, reminding us that policy is ultimately made by people whose experiences shape their understanding of what is at stake.
As the distributed operations concept matures, as alliance partnerships deepen, and as the maritime security cooperation with Vietnam expands, the framework for Pacific security continues to evolve. This evolution is not predetermined or guaranteed to succeed, but it represents a serious effort to adapt American strategy to contemporary realities while maintaining core commitments to allies, partners, and the principles of open and free maritime commerce that have underwritten Pacific prosperity for generations.
In this transformation, Guam stands at the center not as a fixed point but as a dynamic node in a flexible network, much like Under Secretary Cao himself, whose career trajectory embodies the intersection of personal history and strategic necessity that defines this new era in Pacific security.
Robbin Laird is editor of Defense.info and Edward Timperlake is a graduate of the U.S. Naval Academy 1969, received 2 campaign stars from the Vietnam War and is the former CO of VMFA-321.
The featured photo was taken during his October 20 and 21 to Guam and is credited to Joint Region Marianas.