Defense Secretary Ashton Carter’s remarks at the Shangri-La Dialogue on May 30 amounted to a robust, but measured, defense of the United States’ rebalance to the Asia Pacific and its commitment to remain a Pacific power. The speech covered a broad spectrum of U.S. commitments to the region—economic, political, and security—before concluding with an enthusiastic articulation of the United States’ interests in the South China Sea and commitment to pursue them.

The secretary’s visit to Singapore was bookended by trips to Honolulu for the swearing in of Harry Harris as the new commander of U.S. Pacific Command and to Vietnam for meetings with Defense Minister Phung Quang Thanh and other officials. During each, Carter voiced a consistent message that the United States has three major interests in the South China Sea—peaceful resolution, protection of freedom of navigation, and preservation of international law—and is committed to pursuing them.

Carter’s consistent messaging was a welcome step toward convincing both Asian and U.S. audiences that the administration is committed to opposing aggression and defending perceived rights in the South China Sea. He refused to back away from an issue that has become particularly contentious in recent weeks—operations by U.S. ships and planes to assert the right to freedom of navigation and overflight in contested waters. At Harris’s swearing-in, Carter insisted that “the United States will fly, sail, and operate wherever international law allows, as we do all over the world.” He used nearly identical language three days later at the Shangri-La Dialogue, and reiterated it to the media during his flight between and during a press conference following his meeting with Defense Minister Thanh.

But while the determination was unmistakable, what was missing from Secretary Carter’s message was a clear articulation of how claimants’ actions, including artificial island building, threaten international law, why such a threat constitutes a challenge to U.S. national interests, and what specific purpose would be served by proposed “freedom of navigation operations” near certain features. In other words, the trip accurately conveyed U.S. convictions, but not the rationale behind them. In the case of proposed freedom of navigation operations in particular, this has allowed opponents to argue against straw-men, whether purposely or not based on misunderstandings of what the Pentagon is actually considering and why.

To be clear, the Department of Defense is considering sending ships or planes within 12 nautical miles of only those features China has reclaimed that were originally below water at high-tide and not within 12 nautical miles of any other features. This would mean only Mischief Reef and Subi Reef. Nor has this happened yet, despite misrepresentations in the press and by some analysts over where a much-publicized P-8 flight occurred two weeks ago. Such a limited operation would have a very clear purpose in asserting that artificial islands are entitled to only a 500 meter safety zone, not a 12 mile territorial sea. More importantly, it would put yet another bit of pressure on China to clarify the scope and basis of its ambiguous claims.

Carter danced around this clarification at several points during his trip. He told a reporter during his flight to Singapore that the right to a 12 mile territorial sea “does not pertain to features that were submerged, and now are no longer submerged.” And at the Shangri La Dialogue he quipped, “After all, turning an underwater rock into an airfield simply does not afford the rights of sovereignty or permit restrictions on international air or maritime transit.” But the link between that fact of international law and the Pentagon’s proposed freedom of navigation operations was left implicit, and therefore lost on those not well-versed in U.S. naval operations and maritime law.

In fairness, no trip can accomplish everything, and Carter’s message was meant first and foremost to reassure the region about U.S. commitment. The next step must be explaining the how and why. The Pentagon, and the administration at large, must better explain the threat posed to the global maritime commons and international law by China’s extensive claims, and why forcing a clarification of claims is such a vital part of U.S. interests in the sea. Only then will the value of things like freedom of navigation operations make complete sense, and get more robust support both at home and in the region.

And to that end, U.S. policymakers must also be clearer that other claimants will be held to the same standard as China, and any violations of international law they make will be challenged just as vigorously. Carter made an excellent start on that process during his meeting with Defense Minister Thanh, who he urged to forego any further reclamation on Vietnamese-occupied features. The minister made no such promise publicly, but his defense of Vietnamese activities made clear that the two had a candid discussion on the topic.

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.