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

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

The U.S. Navy’s dominance of the world’s oceans has made it an indispensable foreign policy tool as well as a guarantor of global trade, but a mix of challenges is raising difficult questions about its future.
USS Chancellorsville amid a replenishment-at-sea with the aircraft carrier USS Ronald Reagan.
USS Chancellorsville amid a replenishment-at-sea with the aircraft carrier USS Ronald Reagan. John Harris/U.S. Navy/Flickr

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 earth, during times of both war and peace. Yet some experts believe the navy is at a crossroads, facing a set of historic challenges, from budget pressure to China’s naval modernization, that could soon erode its supremacy.

What are the navy’s advantages?

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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.

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The United States is a maritime superpower because its heavily armed warships can travel thousands of miles in a matter of days and linger around points of interest 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 allows for the transport 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 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, may only maintain fleets for coastal regions (green-water) or for rivers and estuaries (brown-water).

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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:

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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, and blockade.

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.

Humanitarian aid. It responds to natural and man-made disasters with medical, food, and logistical and security assistance.

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 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.”  

Tactics 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.

Transits. The USS Curtis Wilbur and the USCGC Bertholf passed through the Strait of Taiwan in March 2019 in a show of support for Taiwan and to demonstrate the “U.S. commitment to a free and open Indo-Pacific.”

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 2018, the U.S. military challenged more than two dozen claimants, including China, Iran, and Slovenia.

Combat capability demonstrations. In the fall of 2018, the U.S. Navy led forces from the North Atlantic Treaty Organization (NATO) in the Trident Juncture exercises, a mock defense of Norway that was in large part intended to deter Russian aggression in Europe. It was the alliance’s largest military exercises in nearly two decades.   

Force-level changes. In 2018, NATO ships increased their presence in the Black Sea by some 50 percent compared to the previous year, responding to Russian operations there, including the seizure of Ukrainian vessels.

Fleet architecture changes. Last year, the U.S. Navy reestablished its Second Fleet in the Atlantic in recognition of a return to “an era of great power competition.”  

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 six 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.

A map showing the locations of U.S. Navy forward deployed bases, showing most in Asia, the Middle East, and the Mediterranean

How big is the navy?

With around 290 ships in recent years, 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 China and Russia each have only one. 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 graphic showing the number of ships, aircraft, and people of the U.S. navy

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 Europe and Asia. “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 recent report on the U.S. Navy [PDF] by the Congressional Research Service. In its latest National Security Strategy, President Donald J. Trump’s administration listed China, Russia, Iran, and North Korea [PDF] as top threats to the United States.

As of mid-2019, the navy’s goal is to build a fleet of 355 ships, which it projects to meet in the 2030s. However, in response to an emerging threat environment in which large warships could become more vulnerable to attack in contested areas, the navy could soon alter this target and look to build a greater number of small surface ships and unmanned vessels.

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 along with 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 ten combatant commands, six 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 in recent months conducted high-profile operations with the navy in the Asia-Pacific region. 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 Trump administration deployed the USS Abraham Lincoln and its strike group to the Arabian Sea in a warning to Iran in early 2019. At any one time, the navy has two to three carrier groups underway, with the remaining groups cycling through maintenance and training.

A graphic showing the composition of a Carrier Strike Group and an Amphibious Ready Group

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 the 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. The rivalry could intensify as China modernizes its navy, building new aircraft carriers, submarines, and frigates.

Meanwhile, China and many other coastal states are claiming controversial maritime rights—like requiring foreign ships to notify a country before sailing through its territorial waters—that if left unchecked could erode the navy’s access. China is also building artificial islands in the South China Sea.

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. Under development by China, Russia, the United States, and others, it can overcome a ship’s air defenses by traveling at several times the speed of sound.

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, in War on the Rocks.

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 144 percent of gross domestic product over the next thirty years.

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