This article is part of Conceptualization of “Maritime Security” in Southeast Asia, a series of analyses produced by experts convened by the S. Rajaratnam School of International Studies.

“Maritime security” in the United States’ national language

English is the working language of the U.S. government. The term “maritime security” is a catch-all in U.S. policy circles. At some levels, particularly in Washington DC’s high-level policy network, it is sometimes used to encompass all naval tasks, but it is commonly used by operational forces as a shorthand to refer to missions also labeled as “non-traditional security,” another vaguely composed term generally used to encapsulate maritime activities short of war.

The United States’ official definition for and usage of maritime security

The United States does not have an official definition for maritime security available in the unclassified realm. The National Maritime Strategy offers one view of maritime security, but only by identifying a roadmap to success, rather than a real definition. This strategy defines the maritime domain and addresses seven “mutually reinforcing implementation plans.” [1] These plans encompass the entirety of the government’s activities and equities in the maritime domain, which leads to a vague, maximalist use of the term. That plan explains “Maritime security is best achieved by blending public and private maritime security activities on a global scale into an integrated effort that addresses all maritime threats.”[2]

“A Cooperative Strategy for 21st Century Seapower”, a document issued in 2007, offered another hint at how the U.S. government viewed maritime security but again stopped short of a definition. Stating that “Creation and maintenance of security at sea is essential to mitigating threats short of war, including piracy, terrorism, weapons proliferation, drug trafficking, and other illicit activities,” this document gives the impression that maritime security is viewed as another way of saying “non-traditional security” or missions outside the so-called “warfighting” functions of the navy.

The United States’ key documents for defining and understanding maritime security

The 2005 National Strategy for Maritime Security is the chief document guiding American maritime security policy, along with its supporting plans: The National Maritime Domain Awareness Plan[3], the Maritime Operational Threat Response Plan[4], the International Outreach and Coordination Strategy[5], the Maritime Infrastructure Recovery Plan[6], the Maritime Transportation System Security Plan[7], the Maritime Commerce Security Plan[8], and the Domestic Outreach Plan[9]. Each document offers departmental plans and responsibilities, identifies areas of focus, and lays out how each line of effort supports the overarching strategy as well as recommendations for effective employment.

Subsequent naval strategies, the 2007 and 2015 editions of “A Cooperative Strategy for 21st Century Seapower” and 2020’s “Advantage at Sea,” also raise the issue of maritime security and offer more hints at an operational definition, if not an official one.

Elements of the United States’ approach to maritime security. Environmental protection, mariner safety, fisheries management, resource management (other than fisheries), counter-terrorism, law enforcement, naval operations, deterrence?

The sweeping U.S. definition of the maritime domain endows it with an accordingly sweeping view of maritime security. “The maritime domain is defined as all areas and things of, on, under, relating to, adjacent to, or bordering on a sea, ocean, or other navigable waterway, including all maritime-related activities, infrastructure, people, cargo, and vessels and other conveyances.”[10] When considering this vast definition, the security of that domain must be equally vast. However, few organizations are structurally prepared to address aspects of maritime security that lie outside their narrowly-defined purview, and whole-of-government coordination is often very limited.

The dividing line for what the U.S. might exclude from the definition of maritime security can be drawn somewhere within the broader remit of naval operations. Maritime security missions are generally viewed as those activities that lie beneath the threshold for armed conflict between states and, in fact, are specifically designated as peacetime activities in the most recent U.S. maritime strategy. The Cooperative Strategy for 21st Century Seapower denotes deterrence, along with sea control, power projection, and humanitarian assistance/distance response, as “core capabilities” separate from maritime security.

Evolution in the United States’ usage of the term “maritime security”

It was around 20 years ago that the term gained prominence within the U.S. government security discourse. Since then, the U.S. national definition and usage of maritime security has not evolved to a meaningful extent. Maritime security took on a new significance and urgency following the September 11, 2001 terrorist attacks in New York City and Washington D.C. Those catastrophic attacks brought about an awakening within the disparate departments of the government as to their vulnerability to disruption via maritime vectors, leading departments and agencies to pursue independent plans for addressing vulnerabilities. Then, in 2004, President Bush directed the Secretaries of the Department of Defense and Homeland Security to lead the creation of a comprehensive National Strategy for Maritime Security to “integrate and synchronize the existing department-level strategies.” Bush’s National Security Presidential Directive 41/Homeland Security Presidential Directive 13 (NSPD-41/HSPD 13) laid out U.S. “policy, guidelines, and implementation actions” intended to enhance U.S. national security and homeland security in the maritime domain. NSPD-41 was later replaced by Barack Obama. Presidential Policy Directive 18 (PPD-18) is titled “National Strategy for Maritime Security,” but has yet to be de-classified and released. Thus, the 2005 document remains the only unclassified policy document available.

The Bush administration also released “A Cooperative Strategy for 21st Century Seapower” which, as mentioned, highlighted several threats short of war as the core of U.S. maritime security policy. “Polic[ing] the global commons and suppress[ing] common threats,” as well as reinforcing freedom of navigation, were at the forefront of the missions identified as crucial to maritime security. Maritime security itself is identified as one of six “core capabilities” of U.S. maritime power; it is listed as something separate from forward presence, deterrence, sea control, power projection, and humanitarian assistance/disaster response, further confirming that it is viewed as something distinct from hard power, warfighting functions of a navy.

“Advantage at Sea,” the Tri-Service Maritime Strategy of the Trump administration, also discusses maritime security without ever truly defining it, but offers additional details that help to sketch out a concept. It identifies the U.S. Coast Guard as the “preferred maritime security partner for many nations vulnerable to coercion,” which both highlights the distinction between how the U.S. conceptualizes coast guard versus navy roles, but also the turn toward using maritime security as a vector of competition with Beijing. “Advantage at Sea” also specifically designates maritime security as a peacetime mission, which seems unrealistically definite given the broad spectrum of tasks within its scope and the increasing risk of state-on-state clashes inherent in some of those tasks. Here, also, maritime security is denoted as a product of maritime governance, encompassing both national and international “laws, policies, and infrastructure” to achieve its objectives.

It could be argued that the concept of strategic competition has prompted at least the beginnings of a shift in U.S. perspectives on maritime security away from terrorism and toward issues that offer new fronts for pressure campaigns against the People’s Republic of China, such as illegal, unreported, and unregulated fishing (IUUF)[11] and environmental degradation. But, in many respects, that shift is limited to areas where the issues can be addressed or wielded to discredit China vis-à-vis its clients and partners, vice a broader commitment to support the prosperity of global maritime communities

Additional context for the United States

The American maritime security apparatus is a multiagency effort and incorporates major actors from multiple departments of the government. Departments of Commerce, Defense, Energy, Homeland Security, State, and Transportation all have key roles and major responsibilities in executing the national strategy. But those departments are also beholden to individual states and local authorities for support within the American federal system.

Strategically, much of the last twenty years of maritime security was developed from a reactive position and reflects both the national trauma of the September 11th attacks and the subsequent Global War on Terror. Thus, many of the measures and plans seem to overemphasize things like terrorist attacks, piracy, and weapons of mass destruction, and traditionally undervalue issues of increasing international importance like IUU fishing and information sharing.

By virtue of its larger budget and considerable capabilities, the Department of Defense leads on many maritime security issues by default. However, identifying any real national chain of command or defined leadership on “maritime security” is problematic.

[1] The National Strategy for Maritime Security, US Government, September 2005,

[2] The National Strategy for Maritime Security, US Government, September 2005, pg. ii,

[3] National Maritime Domain Awareness Plan for National Strategy for Maritime Security, US Government, December 2013,

[4] Global MOTR Coordination Center, US Department of Homeland Security, Last edited September 8, 2011,,interests%20in%20the%20maritime%20domain.

[5] International Outreach and Coordination Strategy for The National Strategy for Maritime Security, US Department of State, November 2005,,to%20ensure%20the%20security%20of

[6] The Maritime Infrastructure Recovery Plan for The National Strategy for Maritime Security, US Government, April 2006,

[7] Maritime Transportation System Security Recommendations for The National Strategy for Maritime Security , US Government, October 2005,

[8] Maritime Commerce Security Plan for The National Strategy for Maritime Security, US Government, October 2005,

[9] Domestic Outreach Plan for The National Strategy for Maritime Security, US Government, October 2005,

[10] The National Strategy for Maritime Security, US Government, September 2005,

[11] United States Coast Guard Outlook on Illegal, Unreported, and Unregulated Fishing, US Coast Guard, September 2020,

About Blake Herzinger

Blake Herzinger is an Indo-Pacific policy specialist and U.S. Navy Reserve officer. He spent nearly a decade in active service with the U.S. Navy as an intelligence officer, with experience in the Middle East and across the Indo-Pacific. He has published on naval affairs, Asian security, and U.S. foreign policy with Brookings, Foreign Policy, War on the Rocks, The Diplomat, and ASPI’s The Strategist, among others.