The People’s Republic of China (PRC) recently suffered a serious embarrassment in front of an international arbitral tribunal convened under authority of the U.N. Convention on the Law of the Sea (UNCLOS). The Permanent Court of Arbitration dismissed decades-old PRC claims to sovereignty over a large swath of the South China Sea. The PRC, however, rejected the tribunal’s decision and appears ready to carry out some sort of escalation to demonstrate that it maintains sovereignty.
That purported sovereignty threatens a core interest of the United States: freedom of navigation on the high seas. The United States needs to develop a flexible, scalable range of options at the tactical level to respond effectively should the PRC escalate actions to reinforce its claims. Conveniently, UNCLOS provides such a range of options that, while only part of a broader solution that should include theater- and political-level escalatory options, could provide U.S. commanders and policymakers a way to respond to any further PRC aggression in a quick, forceful, and unified manner.
The South China Sea Issue
Since coming to power, the Chinese Communist Party (CCP) has claimed sovereignty over a vast portion of the South China Sea, citing so-called historic rights arising from China’s long-standing presence on, use of, and authority over the waters and maritime features of that region.1 But smaller regional powers, including the Philippines, Vietnam, Taiwan, Malaysia, Indonesia, and even tiny Brunei, all claim some portion of that same water space as within their respective exclusive economic zones (EEZs).2 The United States has not backed one claimant over another, but instead insists that U.S. military forces have the right to navigate and conduct peaceful military activities anywhere that international law allows—pretty much any air or water space outside 12 nautical miles of another country’s sovereign territory.3
Thus far, the PRC has proved adept at both countering the competing claims and the United States’ insistence on freedom of navigation and asserting de facto control over the contested waters. On the low end, it has sent paramilitary forces and seagoing “militia” to harass fishermen from the other regional powers and even target U.S. Navy ships operating in the South China Sea.4 Escalating from there, the PRC has built up artificial islands and used military force to seize maritime features.
The PRC looks set to crack open the playbook again after its public rebuke in the Permanent Court of Arbitration. The panel found China had no historic rights to the contested South China Sea waters; and even if such historic rights had existed, the PRC had signed them away when it joined UNCLOS. It further rejected any claim the PRC could make to an EEZ based on the maritime features it had built up over the past few years. Having repudiated the PRC’s claims to sovereignty, the panel then found the Chinese had illegally occupied maritime features within the Philippine EEZ, destroyed protected environments in violation of its international agreements, and harassed non-Chinese fishermen in violation of international law.5
At the tactical level, the United States has responded to past Chinese aggressive actions consistently: freedom of navigation operations (FONOPs) and overflights of contested waterways. Such operations no doubt are useful tools—ships and aircraft traversing the water and air space over Chinese objections demonstrate that the United States does not accept PRC sovereignty and is willing to place forces at risk to show it—but there are two key problems with using FONOPs and overflights alone.
First, though the U.S. Navy has framed its most recent FONOPS as something besides innocent passage, to date all U.S. FONOPS appear to have complied with UNCLOS requirements for innocent passage.6 Any military vessel can transit another country’s territorial waters so long as it does so continuously, expeditiously, and without conducting military- or intelligence-related activities. But innocent passage tacitly acknowledges that someone—here, the PRC—has the authority to demand that ships pass innocently.7 Innocent passage does not apply to aircraft, however, so each U.S. overflight does represent a rejection of PRC sovereignty, but more can be done to emphasize the point.
Second, repeating the same action does not communicate different levels of U.S. disapproval. For example, say the United States conducts innocent-passage FONOPs through the contested waters in response to PRC island construction. The PRC might then declare an air defense identification zone (ADIZ) over the same waters, which the United States would consider a significant escalation. If the United States responds with the same innocent-passage FONOPs or aircraft overflight, its actions would not communicate that it sees the ADIZ as an escalation. This is potentially dangerous. The PRC will not know when it comes against a line the United States will not allow it to cross; it might stumble across unwittingly, leading to hostilities neither side wants.
The PRC likely will respond to the Court of Arbitration decision aggressively. The CCP has stoked nationalist support by taking a hard line on South China Sea issues. To acquiesce to an international decision would risk a domestic backlash.8 Instead, the CCP likely will incrementally escalate provocative activities in the area. In fact, a Chinese admiral already has instructed citizens to prepare for a “people’s war at sea,” and the PRC’s highest judicial authority recently issued a regulation claiming the country could prosecute mariners entering the contested waterways.9
When the PRC acts out, the United States must respond quickly and forcefully. It needs a range of scalable, flexible responses to counter each fresh provocation. That way, the United States can communicate to the PRC that escalatory actions will be met with a concomitantly escalatory U.S. reaction, and U.S. policymakers and commanders would have a list of actions that would communicate different levels of disapproval and resolve.
Conveniently, UNCLOS can be read as a sort of tactical checklist. The treaty lists several activities banned during innocent passage—activities the international community has agreed are unacceptable in a country’s territorial waters. A selection of these can be ranked from least to most serious to create a list of options the United States could follow should China escalate the situation.
Proposed Options for U.S. Vessels
Though it has not ratified UNCLOS, the United States considers the treaty to be customary international law and generally abides by its tenets. UNCLOS requires innocent passage only when transiting another country’s territorial waters, so given the Permanent Court of Arbitration’s decision, the United States can now sail, fly, or operate its forces in the South China Sea as close to the PRC-held maritime features as it chooses without violating international law.
Under UNCLOS a ship must follow specific rules while conducting an innocent passage. First, a vessel must transit in a “continuous and expeditious” manner. It can stop or anchor only if distressed or if aiding another person, vessel, or aircraft in distress. Second, a vessel cannot do anything that might be “prejudicial to the peace, good order or security of the coastal State.” For example, ships cannot:
• Use or threaten to use force
• Exercise or practice with any weapons
• Conduct flight operations
• Launch, land, or take on board any military device (including boats, unmanned vehicles, and towed array sonars)
• Conduct research or surveys
• Jam communications
• If a submarine, transit while submerged10
The U.S. Navy could shape these prohibited activities into a range of options U.S. policymakers and commanders could look to should the PRC act belligerently. If a U.S. ship deliberately carried out a prohibited action, it would be a clear signal that the United States does not recognize PRC sovereignty over the contested waters. Of course, certain activities are more severe than others. For example, a country would see maneuvering within contested waters or deploying a towed array sonar as much less aggressive than actively jamming signals or training with weapons.
Figure 1 suggests one possible ranking of actions by severity, split into three escalatory phases. The innocent passage phase (in blue and green) describes what the United States already does in reaction to PRC aggression. The two additional phases and the actions they include (in yellow and red) are described in detail below.
This escalation phase would have ships carry out normal, nonaggressive underway actions that are prohibited during innocent passage, including:
Surface Ship/Group Maneuvers and Loitering
• Advantage: This would be a relatively low-risk evolution because the ship or group is not restricted in its ability to maneuver and is not employing military equipment, reducing the chance of a mishap or misunderstanding.
• Disadvantage: Maneuvers alone might not send a clear signal that the United States rejects the Chinese claims.
Deploying Destroyer/Cruiser Towed Sonar Array
• Advantage: Many destroyers and cruisers have towed array sonar. Observers can see the array deploying from behind the ship. The array does not involve sending sailors away from the ship.
• Disadvantage: While it can still maneuver, a ship is under some speed, turning, and depth limitations while deploying, streaming, and recovering the array. In addition, the array itself might attract Chinese attention; in the past, Chinese vessels have attempted to interfere with a streamed array.11 Finally, deploying an array is less obvious than some other options; Chinese forces might not notice.
Small Boat Operations
• Advantage: Boat operations are a visible activity that is explicitly banned during innocent passage under Article 19(2)(f). Ships might couple boat operations with an announcement on marine band radio to ensure the Chinese do not think the activity is an attempt to approach or board Chinese vessels.
• Disadvantage: Small boat launch and recovery operations would restrict a ship’s ability to maneuver. They also physically separate the boat crew from the ship, potentially exposing the crew to harassment or capture. The Navy could mitigate this risk by launching an unmanned surface vehicle (USV) rather than a manned boat; however, USVs are not available on most ships.
Flight Operations (Helicopter and Fixed-Wing)
• Advantage: The operation is scalable—helicopter operations from a destroyer or cruiser likely are considered less provocative than fixed-wing flight operations off a large-deck amphibious ship or carrier. Flight operations are visually, acoustically, and electronically obvious and clearly prohibited during innocent passage under Article 19(2)(e). A helicopter or UAV also is harder to isolate or capture than a small boat.
• Disadvantage: Flight operations restrict ship maneuverability; any Chinese interference could lead to a landing or launch accident.
Submarine Surfacing within Contested Waters
• Advantage: The United States could send a submarine into the contested waters while submerged and have it surface within visual range of a Chinese-held maritime feature. This would be an emphatic and jarring signal to the PRC.
• Disadvantage: Such a surprise might lead the PRC commander on the island to act rashly. At the very least, Chinese forces would have an opportunity to gather acoustic, signal, and visual intelligence on the submarine.
These military-focused activities would significantly increase the chance of a misunderstanding or mishap.
Aircraft Sonobuoy Deployment
• Advantage: An aircraft deploying sonobuoys in contested waters would demonstrate the United States does not recognize any Chinese claim. Sonobuoys are not weapons, but rather disposable systems deployed routinely during exercises and intelligence-gathering operations.
• Disadvantage: Physically deploying a disposable sensor might look like some sort of weapon launch. The PRC almost certainly would retrieve the buoy, possibly gleaning some intelligence from it or showing it on video to label the United States as the aggressor.
Surface Ship Shadowing
• Advantage: This would be an escalation the PRC would recognize quickly and to which it would have to react.
• Disadvantage: Shadowing increases the chance that ships will collide.
VHF Message Broadcasting
• Advantage: Broadcasting a message—for example, declaring the U.S. position on the status of the contested waters—on marine band bridge-to-bridge frequencies is technically simple.
• Disadvantage: The PRC might react more aggressively to information operations than to other forms of escalation. Signals Jamming
• Advantage: Signals U.S. displeasure with a given PRC activity.
• Disadvantage: This is a significant escalation that, depending on the PRC interpretation, might lead to a kinetic response.
Weapons Exercises and Practice Firing
• Advantage: There can be no stronger statement against a nation’s claim to control over a waterway than to fire weapons in that waterway without permission.
• Disadvantage: It has the highest chance of a miscalculation or misunderstanding leading to hostilities.
Suppose the U.S. Navy adopted this framework and distributed it to executive branch and congressional policymakers. If, several weeks later, the PRC declared an ADIZ over the South China Sea, those policymakers could select an appropriate response—for example, launching a helicopter from a surface vessel within the ADIZ. Every policymaker would be working from a common picture and would be able to make decisions more quickly, which would allow forces in the theater to carry out the response sooner.
In the aftermath of the Permanent Court of Arbitration’s decision, the PRC likely will take aggressive action to show it controls the South China Sea. If equipped with a flexible, scalable range of options drawn from the list of activities UNCLOS bans during innocent passage, U.S. policymakers could respond quickly and forcefully. That might help demonstrate U.S resolve, deter further PRC escalation, and just maybe avoid hostilities.
2. Sean Mirski, “Dispute in the South China Sea: A Legal Primer,” Lawfare (29 June, 2015), www.lawfareblog.com/dispute-south-china-sea-legal-primer.
3. Michael McDevitt, “The South China Sea: Assessing U.S. Policy Options for the Future,” A CNA Occasional Paper, Center for Naval Analysis and Solutions (November 2014), www.cna.org/cna_files/pdf/IOP-2014-U-009109.pdf.
4. Andrew S. Erikson and Conor M. Kennedy, China’s Maritime Militia, Center for Naval Analysis and Solutions, www.cna.org/cna_files/pdf/Chinas-Maritime-Militia.pdf. Ann Scott Tyson, “Navy Sends Destroyer to Protect Surveillance Ship After Incident in South China Sea,” Washington Post, 13 March 2009.
5. Award, Philippines v. China, PCA Case No. 2013-19 (12 July 2016), 116–17, 254, 415, 397, and 285.
6. Julian Ku, “The Latest US Freedom of Navigation Operation Opens the Legal Door to More Aggressive US Challenges to China’s Artificial Islands,” Lawfare (24 October 2016), www.lawfareblog.com/latest-us-freedom-navigation-operation-opens-legal-door-more-aggressive-us-challenges-chinas.
7. Julian Ku, “We’ve Seen This Movie Before,” Lawfare (11 May 2016), www.lawfareblog.com/weve-seen-movie-latest-us-innocent-passage-freedom-navigation-operation-south-china-sea.
8. Emily Rauhala and Simon Denyer, “Beijing’s Dilemma After South China Sea Ruling: Double Down or Cool Down?” Washington Post, 13 July 2016.
9. Keith Johnson, “China’s Gone Ballistic Since the Hague Ruling,” Foreign Policy, 5 August 2016. James Griffiths, “South China Sea: Beijing Vows to Prosecute ‘Trespassers,’” CNN, 2 August 2016, www.cnn.com/2016/08/02/asia/south-china-sea-supreme-court/.
10. See UNCLOS at Article 18 (2) and 19(2).
11. “Pentagon Says Chinese Vessels Harassed U.S. Ship,” CNN, 9 March 2009, www.cnn.com/2009/POLITICS/03/09/us.navy.china/index.html?iref=24hours.
Lieutenant Proctor is a reserve surface warfare officer currently serving with U.S. Forces Korea, Detachment 102, in Newport, RI, and a third-year law student at Harvard Law School. On active duty he served on board the USS Mason (DDG-87) as antisubmarine warfare officer/boarding officer and with Riverine Squadron Two as a patrol officer and weapons officer. His first reserve tour was as a naval gunfire liaison officer and fires liaison officer with 3d Battalion, 14th Marines.