The United States Is Deeply Invested in the South China Sea

As China postures, Washington remains committed.

By , a senior fellow and the director of the Southeast Asia Program and the Asia Maritime Transparency Initiative at the Center for Strategic and International Studies.
MARCH 31: US and Philippine soldiers take part in a joint live fire exercise as part of the annual 'Balikatan' (shoulder-to-shoulder) US-Philippines war exercises, on March 31 in Crow Valley, Tarlac, Philippines.
MARCH 31: US and Philippine soldiers take part in a joint live fire exercise as part of the annual 'Balikatan' (shoulder-to-shoulder) US-Philippines war exercises, on March 31 in Crow Valley, Tarlac, Philippines.
MARCH 31: US and Philippine soldiers take part in a joint live fire exercise as part of the annual 'Balikatan' (shoulder-to-shoulder) US-Philippines war exercises, on March 31 in Crow Valley, Tarlac, Philippines. Jes Aznar/Getty Images

U.S. Secretary of Defense Lloyd Austin flew to Singapore in June to address the first in-person Shangri-La Dialogue since the outbreak of the COVID-19 pandemic. Japanese Prime Minister Fumio Kishida was officially the headliner, but the contrasting speeches by Austin and Chinese Defense Minister Wei Fenghe drew the most attention.

Wei delivered a tin-eared address threatening Taiwan, warning the United States to stay out of the way, and dismissing the agency of third countries. Austin, by contrast, focused on alliances, partnerships, and international rules as vital. He hailed the United States’ “unparalleled network of alliances and partnerships” as a “profound source of stability” in the Indo-Pacific. And he declared the U.S. commitment to a region “in which all countries—large and small—are free to thrive and to lawfully pursue their interests, free from coercion and intimidation.”

In reflecting on these U.S. commitments, Austin returned to one issue more than any other: the South China Sea. Even when not directly discussing the waterway, his remarks made references to “freedom of the seas,” “maritime-security cooperation,” “threats in the gray zone,” and so on. In this, Austin was the latest in a long line of U.S. officials going back decades to highlight alliance credibility and defense of maritime law as the primary American interests in the South China Sea.

This article is adapted from On Dangerous Ground: America’s Century in the South China Sea by Gregory B. Poling (Oxford University Press, 336 pp., .95, July 2022).
This article is adapted from On Dangerous Ground: America’s Century in the South China Sea by Gregory B. Poling (Oxford University Press, 336 pp., .95, July 2022).

This article is adapted from On Dangerous Ground: America’s Century in the South China Sea by Gregory B. Poling (Oxford University Press, 336 pp., $39.95, July 2022).

U.S. Secretary of Defense Lloyd Austin flew to Singapore in June to address the first in-person Shangri-La Dialogue since the outbreak of the COVID-19 pandemic. Japanese Prime Minister Fumio Kishida was officially the headliner, but the contrasting speeches by Austin and Chinese Defense Minister Wei Fenghe drew the most attention.

Wei delivered a tin-eared address threatening Taiwan, warning the United States to stay out of the way, and dismissing the agency of third countries. Austin, by contrast, focused on alliances, partnerships, and international rules as vital. He hailed the United States’ “unparalleled network of alliances and partnerships” as a “profound source of stability” in the Indo-Pacific. And he declared the U.S. commitment to a region “in which all countries—large and small—are free to thrive and to lawfully pursue their interests, free from coercion and intimidation.”

In reflecting on these U.S. commitments, Austin returned to one issue more than any other: the South China Sea. Even when not directly discussing the waterway, his remarks made references to “freedom of the seas,” “maritime-security cooperation,” “threats in the gray zone,” and so on. In this, Austin was the latest in a long line of U.S. officials going back decades to highlight alliance credibility and defense of maritime law as the primary American interests in the South China Sea.

Reflecting on that history helps explain why Washington cares so much about a dispute over rocks and reefs half a world away. And it suggests what would be lost should China compel the United States to abandon these longstanding interests. Given Beijing’s campaign of militarization and coercion over the last decade, that is for the first time a real possibility, which makes it important to understand the stakes involved.


The oldest U.S. interest at stake in the disputed waterway is the freedom of the seas and maritime law. U.S. leaders have seen maintenance of the free seas as vital to national prosperity and security for more than two centuries. Few interests have been as consistent over the course of American history.

That commitment drove the young United States to launch its first military forays abroad in two wars with the Barbary States. It contributed to the outbreak of the War of 1812 fought against Britain. Before long, the desire to protect the nation’s maritime rights drew the U.S. Navy into the Pacific Ocean with the 1835 creation of the East India Squadron. Except for a brief interlude during the American Civil War, U.S. naval vessels have operated continuously in Asia ever since.

Beijing’s claims in the South China Sea, especially to historic rights throughout the so-called nine-dash line, threaten the centuries-old U.S. commitment to freedom of the seas. That commitment helped underwrite American prosperity and security. Today it stabilizes international commerce, mitigates naval tensions, and guarantees equitable access to resources.

The United Nations Convention on the Law of the Sea (UNCLOS) represents the work of decades spent negotiating and codifying those freedoms. The treaty has unmatched legitimacy as a truly global effort. China had as much say in its creation as any state. And the same goes for most of China’s neighbors, which is why they cling to it so fiercely. In the United States, a small but vocal minority stands in the way of ratification. But for every American involved in maritime affairs, whether naval, commercial, or scientific, UNCLOS is effectively the law of the land.

China’s claims are so antithetical to the convention that it could not long survive their acceptance. If Beijing could claim 1,000 miles of ocean and seabed, why shouldn’t others? The effects of an unraveling UNCLOS would threaten American interests from the Arctic to the Persian Gulf. Russia already toys with the idea of historic rights in the former. And Iran would seize on any opportunity to legitimize its efforts to control the latter.

But China’s claims undermine more than just this one convention. They strike at the most basic principle of international law: the equality of states. China’s leadership would treat international law the way it does domestic law—as a tool of power but never a constraint on it. Allowing UNCLOS to be undermined without significant cost would only confirm that. Beijing would rightly conclude that if it can dispense with something as widely respected as the law of the sea, then more contested norms are fair game. And that would inform its approach to competition across the board, from economics to space and everything in between.

The second abiding U.S. interest in the South China Sea, at least since the end of World War II, has been to uphold defense commitments without being dragged into the arguments of U.S. allies over disputed sovereignty. The U.S. alliance network, along with American territories in the region, have made the United States a resident power and helped maintain stability in Asia. They allow the country to forward-deploy significant military forces thousands of miles from the homeland, deterring aggression and quickly responding to regional security challenges. This in turn keeps the United States and its allies safe and their shared interests protected.

America’s earliest involvements in the South China Sea during the prewar decades sprung from its colonial presence in the Philippines. When the Philippines gained formal independence in 1946, neither side wanted U.S. forces to leave amid fear of Soviet encroachment in Asia. They inked a Military Bases Agreement in 1947 and a Mutual Defense Treaty in 1951, creating America’s earliest security alliance in the Pacific. This was the first step in the creation of the U.S. alliance system that persists in Asia to this day.

The United States soon inked similar defense treaties with Australia, New Zealand, Taiwan, Japan, and South Korea. Then came semiformal alliances with Thailand and South Vietnam. Among this club, the Philippines, Taiwan, and South Vietnam all staked claims to disputed islands in the South China Sea. During this time, the top U.S. priority in the disputes was to maintain credibility without alienating any of the three allies. And that meant remaining neutral and urging calm.

That changed over the course of the 1970s. Saigon fell, the victorious forces of North Vietnam moved into the Spratly Islands, China violently expanded its footprint in the Paracel Islands, and the United States abrogated its treaty with the Taiwanese government. In the span of a few years, Manila found itself Washington’s only ally left in the dispute, facing potential aggression from either Hanoi or Beijing. At the same time, perceived abandonment of South Vietnam and Taiwan raised worries about the credibility of other U.S. defense commitments. Philippine officials wondered if the alliance had become a one-way street—were they making themselves a target by hosting U.S. bases without even a credible American commitment of support in the South China Sea, where they faced potential violence? This kicked off a cycle of negotiations over the scope and value of the alliance. In many ways, that cycle continues to this day.

Over the past four decades, Washington has slowly clarified that the U.S.-Philippines Mutual Defense Treaty applies to any attack on Philippine forces in the South China Sea. It continues to balance that commitment with its long-standing neutrality on territorial claims. There have been some close calls on both sides, but Washington has determined over and over that its oldest alliance in Asia is too valuable to let slip away. Manila has repeatedly reached the same conclusion.

The U.S.-Philippine relationship is at once vital and conflicted. It is built on more than a century of cultural interchange, deep personal connections, shared sacrifice, and common interests. But it is also clouded by the history of colonization, political interference, unequal economic relations, and a huge disparity in power. The last leaves one side often fearing abandonment and the other entrapment.

Manila would find it all but impossible to defend its maritime rights from growing Chinese encroachment without U.S. military support. And were the United States to be seen as abandoning the Philippines to Chinese aggression, it would ripple well beyond the South China Sea. The ability of the United States to project power and respond to crises in Southeast Asia would be severely compromised if it lost access to Philippine territory. Other allies and partners would naturally question the U.S. capability and will to remain a regional security provider. The American alliance network would face a crisis—of both confidence and capability—at a time when it is needed most. The rise of Chinese power and its clear revisionist intent would make the rapid diminution of U.S. influence in Asia far more destabilizing than it was even in the 1970s.

The United States has been involved in the South China Sea disputes almost from their conception. That has occasionally taken the form of clear-eyed, proactive defense of American interests. But more often, policymakers have been entangled by circumstance. Their attention elsewhere, they would be unexpectedly roused by a crisis or the demands of regional allies. They would need to quickly assess the national interest. And then the disputes would return to the margins of U.S. policy until the next crisis. The results were unsurprisingly mixed.

This time, the stakes are higher and the South China Sea disputes are not going to fade into the background. If the United States is going to secure its national interests, it will need to be more deliberate about identifying and pursuing them. It has long defended the freedom of the seas and a credible alliance network in Asia. The maintenance of both has helped ensure the national security and prosperity of the United States and its partners. Those interests were from time to time challenged in the South China Sea. But now, China’s actions in the disputes threaten to fatally undermine them. Facing this challenge from a peer competitor—the first in decades—the United States must hold to a realistic assessment of its own interests.

As Austin said, “Today, the Indo-Pacific is at the heart of American grand strategy.” And that strategy cannot succeed without defending the rules and alliances at stake in the South China Sea.

Gregory B. Poling is a senior fellow and the director of the Southeast Asia Program and the Asia Maritime Transparency Initiative at the Center for Strategic and International Studies.

Join the Conversation

Commenting on this and other recent articles is just one benefit of a Foreign Policy subscription.

Already a subscriber? .

Join the Conversation

Join the conversation on this and other recent Foreign Policy articles when you subscribe now.

Not your account?

Join the Conversation

Please follow our comment guidelines, stay on topic, and be civil, courteous, and respectful of others’ beliefs. Comments are closed automatically seven days after articles are published.

You are commenting as .

More from Foreign Policy

U.S. President Joe Biden listens to remarks in the Rose Garden at the White House in Washington on May 19.
U.S. President Joe Biden listens to remarks in the Rose Garden at the White House in Washington on May 19.

Russia’s Defeat Would Be America’s Problem

Victory in Ukraine could easily mean hubris in Washington.

Russian and Belarusian troops take part in joint military exercises.
Russian and Belarusian troops take part in joint military exercises.

Russia’s Stripped Its Western Borders to Feed the Fight in Ukraine

But Finland and the Baltic states are still leery of Moscow’s long-term designs.

Electricity pylons are shown under cloudy skies during rainfall near Romanel-sur-Lausanne, Switzerland, on Sept. 15.
Electricity pylons are shown under cloudy skies during rainfall near Romanel-sur-Lausanne, Switzerland, on Sept. 15.

Europe’s Energy Crisis Is Destroying the Multipolar World

The EU and Russia are losing their competitive edge. That leaves the United States and China to duke it out.

European Commission President Ursula von der Leyen announces new European Union energy policies at the bloc’s headquarters in Brussels, on Sept. 7.
European Commission President Ursula von der Leyen announces new European Union energy policies at the bloc’s headquarters in Brussels, on Sept. 7.

With Winter Coming, Europe Is Walking Off a Cliff

Europeans won’t escape their energy crisis as long as ideology trumps basic math.