After months of internal debate within the Obama administration, the guided missile destroyer USS Lassentransited within 12 nautical miles of Subi Reef, one of China’s artificially-built features in the South China Sea, on October 27 in what is termed a “freedom of navigation” (FON) operation. It was accompanied by two maritime surveillance aircraft, a P-8A Poseidon and a P-3 Orion.

Q1: What was the purpose of the operation?

A1: FON operations are intended to challenge maritime claims that the United States considers excessive under international law. The U.S. military has been conducting these operations regularly all over the world since 1979; in 2014 U.S. forces used FON operations to contest claims made by most of the South China Sea claimants, including China. However, the United States has not conducted FON operations inside 12 nautical miles of any feature in the South China Sea since 2012, according to Assistant Secretary of Defense David Shear. This particular operation was intended to assert that the United States does not recognize a 12-nautical-mile territorial sea or any other maritime entitlements generated by reefs that were originally submerged but on which China has built artificial islands. It was not meant to challenge China’s claim to Subi Reef itself.

FON operations are not primarily about military deterrence or diplomatic messaging, though in a politically charged atmosphere like the South China Sea those play a role. At its root, FON operations are legal exercises to reinforce the United States’—and in this case the overwhelming majority of the international community’s—interpretations of international maritime law. They are a means to ensure that U.S. naval, coast guard, and civilian ships, and by extension those of all nations, maintain unrestricted access to their rights at sea. In this particular case, the United States also needed to demonstrate its commitment to freedom of navigation as regional allies and partners had grown concerned in the wake of China’s massive island building and construction of potential military facilities including airstrips in the Spratlys.

The U.S. government takes no position on the territorial disputes in the Spratly Islands, but does take a strong position on what kinds of claims are made to the waters surrounding those features. The United States shares the concerns of regional states that the intentional ambiguity of China’s claims to vast stretches of water and seabed are a leading driver of tensions in the South China Sea. U.S. officials regularly call on all parties to the dispute to bring their claims into accordance with international law. The FON operation around Subi is part of that overall strategy—it is a practical demonstration that the United States will not accede to maritime claims that violate international law, and it places pressure on China’s leaders to give a legal rationale for their objections to the operation.

Q2: Has China claimed a territorial sea around Subi Reef?

A2: China has been deliberately ambiguous about its claims to waters in the South China Sea. Although it has not specified exactly what its claim is around each of the built-up rocks or low-tide elevations in the Spratlys, China’s 1992 law on the territorial sea claims 12-nautical-mile territorial waters from all Chinese territory without distinction. In addition, the Chinese foreign ministry has implied that China claims territorial sovereignty over waters and airspace surrounding submerged reefs. In a statement on October 9, a foreign ministry spokesperson said that China does not “condone infringement of China’s territorial sea and airspace by any country under the pretext of maintaining freedom of navigation and overflight.” People’s Liberation Army Navy (PLAN) ships have warned U.S. surveillance aircraft flying near its artificial islands, including Subi Reef, to stay away from its undefined “military alert zone.”

Q3: How has China reacted to the FON operation?

A3: Two PLAN vessels, the Lanzhou (a Type 052C missile destroyer) and Taizhou (a Type 053 frigate), shadowed theLassen and issued warnings to get out of the waters around Subi, but apparently did not interfere with the operation. Since U.S. media has been reporting that the Obama administration was considering conducting a FON operation for the past six months, China was well prepared for this eventuality, even though Washington did not notify Beijing in advance.

China’s foreign ministry spokesman Lu Kang criticized the exercise, saying the U.S. Navy ship “illegally entered” the waters near the islands “without receiving permission from the Chinese government,” “threatened China’s sovereignty and security interests,” and “endangered regional peace and stability.” This language suggests that China in fact does claim a 12-nautical-mile territorial sea around formerly submerged reefs that it has built into artificial islands, which is contrary to the United Nations Convention on the Law of the Sea. In addition, the spokesman warned that China would “firmly respond to any deliberate provocation by any country.” Vice Foreign Minister Zhang Yesui summoned U.S. ambassador to China Max Baucus to protest what he claimed was a “serious provocation.”

Q4: How are other regional states likely to respond?

A4: The majority of countries in the region are likely to welcome the U.S. decision to conduct FON operations around Chinese artificial islands that were previously submerged reefs. The other claimants, non-claimants in maritime Southeast Asia, as well as nations outside the region, such as Japan and Australia, are increasingly concerned about China’s militarization of its islands, its coercive behavior, and the possibility that China might declare an Air Defense Identification Zone in the South China Sea as it did in the East China Sea in November 2013. Australia, Japan, and the Philippines have issued statements supporting the U.S. action. Most other nations will likely opt to refrain from making public statements to avoid provoking China’s ire.

Q5: What comes next?

A5: U.S. officials have made clear that this will not be the last FON operation in and around the Spratly Islands. There will be follow-up operations around other Chinese features and perhaps around those of other claimant nations in order to further the message that FON operations are regular, non-provocative aspects of U.S. policy not specifically targeted at China, and to challenge other types of excessive claims (the recent operation was tailored specifically at objecting to the ability of an artificial island to generate a territorial sea). These operations will be narrowly defined to achieve legal ends, and will happen with regularity but not so frequently as to be intentionally provocative. For the same reason, it is unlikely that the United States will seek to perform joint FON operations with other regional states, though it continues to urge Australia, Japan, and other regional partners to perform operations of their own to assert their rights in the South China Sea.

Follow-on FON operations might include a transit or patrol around Mischief Reef, which like Subi Reef was submerged at high-tide before China’s reclamation work transformed it. They could include “innocent passage” transits within 12 nautical miles of some of China’s other features in the Spratlys that were above water before their expansion. Innocent passage under international law is the right of civilian and military vessels to peacefully sail through the territorial waters of a foreign country as long as they do not perform activities not directly related to transit (including military exercises and intelligence gathering). Chinese navy ships made an innocent passage through U.S. waters around the Aleutian Islands in early September. And they could, and in fact should, include similar operations around rocks or islands occupied by the Philippines, Vietnam, and Malaysia in the Spratlys, as well as Vietnamese-occupied submerged features, as it has in the past.


This article originally appeared as part of Critical QuestionsCritical Questions is produced by the Center for Strategic and International Studies (CSIS), a private, tax-exempt institution focusing on international public policy issues. Its research is nonpartisan and nonproprietary. CSIS does not take specific policy positions. Accordingly, all views, positions, and conclusions expressed in this publication should be understood to be solely those of the author(s).

© 2015 by the Center for Strategic and International Studies. All rights reserved.

About Michael Green

Michael Jonathan Green is senior vice president for Asia and Japan Chair at CSIS and an associate professor at the Edmund A. Walsh School of Foreign Service at Georgetown University. He served on the staff of the National Security Council (NSC) from 2001 through 2005, first as director for Asian affairs, and then as special assistant to the president for national security affairs and senior director for Asia.

About Bonnie Glaser

Bonnie S. Glaser is a senior adviser for Asia and the director of the China Power Project at CSIS, where she works on issues related to Chinese foreign and security policy. She is concomitantly a non-resident fellow with the Lowy Institute in Sydney, a senior associate with CSIS Pacific Forum, and a consultant for the U.S. government on East Asia. Follow her on Twitter at @BonnieGlaser.

About Gregory Poling

Gregory B. Poling is senior fellow for Southeast Asia and director of the Asia Maritime Transparency Initiative at CSIS. He oversees research on U.S. foreign policy in the Asia Pacific, with a focus on the maritime domain and the countries of Southeast Asia. His research interests include the South China Sea disputes, democratization in Southeast Asia, and Asian multilateralism.