Sea Power: The U.S. Navy and Foreign Policy

Introduction

Like the British Royal Navy more than a century before it, the U.S. Navy has a command of the sea that affords the United States unrivaled international influence. For decades, its size and sophistication have enabled leaders in Washington to project American power over much of the world, during times of both war and peace. Yet, some experts believe the navy is at a crossroads, facing a set of historic challenges, including budget pressure and China’s naval modernization, that could erode its supremacy.

What are the navy’s advantages?

By its use of the sea, which covers nearly three-quarters of the earth, a navy can do things that land-based forces cannot. It can provide extraordinary access to points of interest around the globe, patrolling vital waterways and maneuvering to distant shores and population centers.

The United States is a maritime superpower because its heavily armed warships can travel thousands of miles in a matter of days and linger at locations without imposing on another country’s sovereignty and, if desired, without provoking much attention. This makes the navy an incredibly powerful tool, especially for responding to international crises.

At the same time, the navy’s superior lift capability, the ability to transport equipment and personnel over long distances, allows for the delivery of firepower, fuel, food, and other cargo needed to sustain distant combat operations. “The crucial enabler for America’s ability to project its military power for the past six decades has been its almost complete control over the global commons,” wrote U.S. Joint Forces Command in a 2010 strategy document [PDF]. 

What is the navy’s role?

The roles that a navy serves depend on its capabilities. The United States is one of only a handful of countries that have a so-called blue-water navy, which can operate across the open ocean. Others, constrained by geography or resources, can only maintain fleets for coastal regions (green-water) or for rivers and estuaries (brown-water).

The navy’s power is rooted in its capacity to use or threaten force, but it also has significant diplomatic and constabulary functions. In fulfilling these, the U.S. Navy regularly deploys with the Marine Corps, an amphibious assault force, and the Coast Guard, which enforces maritime law and conducts search and rescue operations, among other functions.

These three naval services have several interrelated capabilities that they say constitute U.S. sea power [PDF]:

Forward presence. The navy deploys to various regions where the United States has a strategic interest. This demonstrates a persistent, but not permanent, U.S. commitment.

Deterrence. It discourages adversaries from acting against the United States and its allies and partners. For example, U.S. Navy ballistic-missile submarines serve as a leg of the nuclear triad, particularly valued for their ability to hide and stay a credible threat during a potential nuclear conflict.

Sea control. It exercises control over the sea, at least in certain areas for certain lengths of time. Sea control provides a freedom of action that is required for the pursuit of other objectives, such as shipping protection, military sealift—which includes using cargo ships to deploy military assets—and blockades.

Power projection. It can threaten or direct strikes—from ballistic-missile attacks to amphibious assaults—against targets ashore for sustained periods.

Maritime security. It protects seaborne commerce—some 90 percent of global trade travels by ship—and generally maintains order at sea. Operations include counterpiracy, drug interdiction, environmental protection, and other law enforcement measures.

Humanitarian aid. It responds to natural and man-made disasters with medical, food, and logistical and security assistance. For example, the U.S. military constructed a large pier several miles off the shore of the Gaza Strip to allow cargo ships to offload humanitarian aid shipments for the enclave.

How is the navy used for diplomacy?

Maritime powers, including the United States, have long used navies to influence the behavior of allies and adversaries during times of peace.

These types of naval operations may be intended to support, reassure, deter, or threaten different actors. Some experts have used the term “gunboat diplomacy” to refer to the more coercive use of navies; other analysts have characterized the political use of naval power as “armed suasion.”  

Operations the navy employs for diplomatic effect include:

Port calls. For instance, the USS Carl Vinson sailed into Da Nang, Vietnam, in 2018 in a signal to China that U.S.-Vietnam ties were warming. It was the first U.S. carrier to visit Vietnam since the United States warred with Communist forces there decades ago; the two governments officially upgraded bilateral ties in 2023.

Transits. The USS John Finn passed through the Strait of Taiwan in January 2024 following Taiwanese presidential and parliamentary elections to demonstrate the “United States’ commitment to upholding freedom of navigation for all nations as a principle,” according to a statement from the fleet’s commander. 

Freedom of navigation operations. The navy regularly conducts such operations, also known as FONOPs [PDF], to challenge what it sees as excessive maritime claims by other states. In fiscal year 2022, the U.S. military challenged [PDF] more than a dozen claimants, including China, Iran, and Russia.

Combat capability demonstrations. In January 2024, the navy kicked off Steadfast Defender 2024, the largest military exercise conducted by the North Atlantic Treaty Organization (NATO) in decades. The six-month-long operation intends to showcase the alliance’s ability to move reinforcements across the Atlantic to support allies in Europe, if they were to come under attack.

Force-level changes. Since Russia invaded Ukraine in 2022, NATO navies have significantly increased their presence in the Black Sea, sending additional ships and troops to the area in response to Russian operations there.

Fleet architecture changes. In 2018, the U.S. Navy reestablished its Second Fleet in the Atlantic in recognition of a return to “an era of great power competition.” The navy has since committed to a fleet modernization plan [PDF] that increases the fleet size 5 percent by 2045, replacing older units with next-generation unmanned warships and submarines.

More broadly, navies can exert influence by their mere presence and normal operations. For instance, the navy is a cornerstone of U.S. military alliances with far-flung states such as Japan and the Philippines.

Where is the U.S. Navy deployed?

The navy has seven fleets covering different parts of the world, and it maintains more than a dozen permanent installations outside the contiguous United States, with multiple locations in Italy and Japan.

How big is the navy?

With around 290 ships, the U.S. Navy is not the largest in the world, but it’s the most powerful. The United States has eleven aircraft carriers, the largest military vessels in the world, while rivals China and Russia have three and one, respectively. However, such numerical comparisons are of limited value, and defense analysts caution that the yardstick should be whether the navy, as well as other services, are equipped to fulfill the country’s security and foreign policy objectives.

A rationale for U.S. forces in recent decades has been defending against the rise of adversaries that could deny the United States access to important allies and markets in Asia and Europe. “The traditional U.S. goal of preventing the emergence of a regional hegemon in one part of Eurasia or another has been a major reason why the U.S. military is structured with force elements that enable it to cross broad expanses of ocean and air space and then conduct sustained, large-scale military operations upon arrival,” says a 2024 report [PDF] by the Congressional Research Service. In its latest National Security Strategy [PDF], President Joe Biden’s administration listed outcompeting China, constraining Russia, and reigning in weapons proliferation in Iran and North Korea as the United States’ top global priorities.

As of mid-2023, the navy’s goal is to build a fleet of 381 manned ships, including 31 larger amphibious ships, which it projects to meet in the 2030s. Additionally, the navy plans to add 150 unmanned vessels by 2045 as part of its goal of creating a “hybrid force” that operates above and below the waterline, then Chief of Naval Operations Admiral Michael Gilday said in 2023 [PDF].

Who leads the navy?

The navy bureaucracy is led by a civilian, the secretary of the navy, and a senior military officer, the chief of naval operations (CNO). The Marine Corps also falls under the Department of the Navy but has its own senior officer, the commandant of the Marine Corps. Both the CNO and the commandant serve alongside the heads of the air force, army, and National Guard as members of the Joint Chiefs of Staff, a group that advises the president and secretary of defense on military matters.

The chiefs, however, do not have operational command over their services. The chain of command runs from the president to the secretary of defense to the combatant commanders, with the chairman of the Joint Chiefs of Staff serving as a conduit. There are eleven combatant commands—seven geographic and four functional—all led by four-star officers. Some commands, such as the Indo-Pacific Command (formerly Pacific Command), have been dominated by one service—in this case, the navy.

The coast guard is a military service but not part of the navy, although it often partners closely with it in situations that have a constabulary component, such as international sanctions enforcement. For instance, the coast guard has conducted high-profile operations with the navy in the Asia-Pacific region, such as stopping illegal oil and coal shipments that violated UN sanctions on North Korea. It is a component of the Department of Homeland Security but can operate as an arm of the navy during wartime.

How does the navy deploy?

The navy deploys depending on national priorities and the mission at hand. Perhaps the most well-known formation is the carrier strike group, centered around a nuclear-powered aircraft carrier and its air wing of dozens of warplanes. Providing protection and other support for the group are, generally, a guided-missile cruiser, several guided-missile destroyers, an attack submarine, and a supply ship. More than seven thousand sailors and Marines serve each group.

As a recent example, the Biden administration deployed the USS General R. Ford and its strike group to the eastern Mediterranean Sea as a show of support for Israel following the October 7, 2023, attack by Palestinian militant group Hamas.  At any one time, the navy has two to three carrier groups underway, with the remaining groups cycling through maintenance and training.

Another common formation is the amphibious ready group, organized around an assault ship and a marine expeditionary unit, and accompanied by a transport dock ship and a dock-landing ship. Carrying a full complement of attack planes and helicopters, flattop assault ships such as the USS Wasp and Kearsarge could easily be mistaken for aircraft carriers though they are not classified as such. The navy also has two to three of these groups underway at any time.

What challenges is the navy facing?

The navy faces headwinds as it plots its course for the next several decades. Leaders are particularly watchful of the western Pacific, where the navy is jockeying with China for influence. The United States has long dominated the region’s vast waters, but China is pushing hard to gain sway over many of the small island countries with development loans and other inducements. The sparsely populated islands are prized not for their commercial potential but for their strategic value, analysts say.     

“This is a pre-conflict type of shadow game, a geopolitical non-war version of island-hopping. The Pacific has become strategic again for the first time since World War II,” international security expert Euan Graham told the Financial Times in 2019. The rivalry could intensify as China modernizes its navy [PDF], building new aircraft carriers, submarines, and frigates. A 2022 security cooperation deal between China and the Solomon Islands heightened these concerns. 

Meanwhile, China and many other coastal states are asserting controversial maritime rights—such as requiring foreign ships to notify them before sailing through their territorial waters—that if left unchecked could erode the navy’s access. China is also making increasingly expansive territorial claims and building artificial islands in the South China Sea, clashing with neighboring states that have competing claims, such as the Philippines.

Defense experts also cite the challenge posed by proliferation of anti-access and area denial capabilities. These weapons, known as A2/AD, are intended to push naval adversaries farther out to sea or to keep them in port. One of the most talked about of these threats is the hypersonic anti-ship missile. Russia reportedly fired a hypersonic missile in a February 2024 attack on Kyiv, Ukraine, marking the first time this advanced weapon has been used in battle. Some naval experts believe these looming threats will usher in a new era of naval warfare in which the aircraft carrier will have no place. The U.S. carrier and amphibious fleet “both share a critically important place in the overall fleet architecture—they are both unaffordable anachronisms of a bygone era,” writes Noel Williams, a naval expert and retired Marine officer, for War on the Rocks in 2019.

Others say the carrier will likely adapt and sail on. “Future carriers may have different designs, capabilities, and even names, but the U.S. government’s need to project power from the sea will not change,” says U.S. Navy Captain Kevin Brand, a former CFR military fellow.

Some claim that the biggest long-term threat to the navy, and to the U.S. military generally, is not foreign but domestic: a shrinking budget. Economists expect the challenge to grow as the U.S. population ages and the country spends more on health care, social security, and interest on the national debt, which is on course to roughly double to around 190 percent of gross domestic product (GDP) over the next thirty years.