The U.S. Freedom of Navigation Program was formally established in 1979 to challenge excessive maritime claims around the world and to advocate for “the rights and freedoms of the international community in navigation and overflight,” as later articulated in the 1983 U.S. Ocean Policy.1 Recently, the U.S. State and Defense Departments have worked in concert to assert these rights, in the face of contrary claims by more than 20 countries each year.2
Since 2017, the annual freedom of navigation operations (FONOPs) summary provided to Congress has highlighted the South China Sea and its islands as one geographic focus. The Navy conducted eight FONOPs in the South China Sea between January 2017 and September 2018. In public remarks in 2019, former U.S. Pacific Fleet Commander Admiral Scott Swift stated that South China Sea assertions should occur at least every six weeks, emphasizing that “consistency is important.”3
While a plan was submitted to the White House in April 2017 to streamline the FONOPs approval process, U.S. Indo-Pacific Command is inhibited by finite quantities and limited availability of surface combatants and patrol and surveillance aircraft. The chair of the House Armed Services Committee remarked in February 2020 that “our current fleet is strained to handle the steady state demand we are currently experiencing.”4 However, an emerging class of solar-powered unmanned aerial vehicles (UAVs) that can operate in the stratosphere may be well-suited to alleviate availability constraints and competition for tasking, while providing theater commanders with new operational flexibility.
Termed high-altitude pseudo-satellites (HAPS), these lightweight composite, slender-winged UAVs operate well above conventional air traffic and most terrestrial weather and can be commanded with a satellite communication link. Other than an orbiting satellite, high-altitude balloon, or Lockheed U-2 spy plane, no other system provides as extensive a collection footprint.
The most technologically mature of these systems is Zephyr, developed by Airbus. The Zephyr S model conducted its maiden flight in Arizona in July 2018 and surpassed the 14-day flight endurance record previously set by a HAPS prototype, remaining aloft for nearly 26 days at an average altitude of 70,000 feet.5 Zephyr has a 25-meter wingspan and 5-kilogram payload capacity, and it can be outfitted with electro-optical/infrared (EO/IR) sensors and communications relay equipment. A larger version will feature a 33-meter wingspan and 20-kilogram payload and could support a maritime synthetic aperture radar (SAR) and high-capacity communications.6 In 2016, the British Ministry of Defence ordered three Zephyr S vehicles as part of a £13 million ($17.2 million) contract for concept demonstrations.7
Zephyr is not without its competitors. The maiden flight of BAE’s Persistent High-Altitude Solar Aircraft (PHASA) occurred in February; its technical specifications include a 35-meter wingspan, 15-kilogram payload capacity, 65,000-foot operating altitude, and a theoretical endurance of up to a year aloft.8 Silicon Valley startup Zenith Aerospace pitches its RS-37 Sentinel vehicle as marrying the endurance of a satellite with the flexibility of an aircraft, advertising the ability to image 300 square kilometers per frame and achieve image resolutions of 10 centimeters while remaining aloft for six months.9
The defense science and technology agencies of both the United Kingdom and Australia have sponsored HAPS development efforts, and because both countries also have directed their own independent naval patrols through the South China Sea, opportunities abound for HAPS collaboration between the United States and these Five Eyes allies.10 Maintenance infrastructure and experienced ground crew already reside in Australia, and because these UAVs can maintain flight for weeks or longer, the bases are within range of the South China Sea and other locations previously identified for FONOPs, including the Java Sea, Sulu Sea, and Gulf of Thailand.
Two years ago, Airbus opened its primary launch and recovery base for Zephyr operations in Western Australia, touting the region’s clear weather and low air-traffic density.11 BAE’s PHASA flew from the Woomera Test Range in South Australia.12
HAPS UAVs offer notable advantages over imagery or signals intelligence satellites. A satellite in low-earth orbit has a period of 90–104 minutes and is overhead any given terrestrial location only a fraction of the time; gaps in coverage exist even when employing a constellation of satellites.13 A solar-powered HAPS UAV offers extreme persistence and can loiter over a fishing fleet, drilling rig, or contested island for days or weeks at a time. And while HAPS vehicles can be employed for FONOPs, orbiting satellites are unable to challenge territorial claims. Article II of the 1967 Outer Space Treaty states that space “is not subject to national appropriation by claim of sovereignty,” guaranteeing satellites worldwide overflight rights.14
HAPS UAVs could make airspace incursions in the vicinity of Chinese-occupied features to challenge Beijing’s territorial claims on a consistent, recurring basis— even several times per week—releasing crewed assets, such as P-8A Poseidon maritime patrol aircraft and Arleigh Burke–class destroyers, for dynamic tasking and distancing them from the risks posed by Chinese fighters or surface combatants. In April 2001, the collision between a People’s Liberation Army Navy J-8 and a U.S. Navy EP-3 killed the Chinese pilot and caused the American crew to divert for an emergency landing on Hainan Island.15 And in October 2018, the Chinese destroyer Lanzhou came within meters of colliding with the USS Decatur (DDG-73) near Gaven Reef, requiring the U.S. destroyer to make immediate maneuvers.16 Cruising at 70,000 feet, HAPS UAVs are too high to be intercepted by adversary fighter aircraft. They could be, however, harassed by lasers or radio-frequency jamming like any other platform, or shot down by missiles, though with no harm to any onboard crew members.
The Zephyr S costs roughly $5 million per unit, and the competitive price and unrivaled persistence of HAPS UAVs make them an attractive choice for FONOPs and maritime surveillance. By comparison, the Navy’s MQ-4C Triton UAV costs more than $100 million per unit and has an endurance of roughly 30 hours. The Zephyr and its peers appear ideal candidates for the middle tier of acquisition (MTA) pathway, which encompasses both a rapid prototyping option and a rapid fielding option aimed at deploying new capabilities within five years.17 Inception under the MTA framework offers exemptions from some of the cumbersome reviews and approvals associated with traditional defense acquisition processes.
Naval aviation also boasts a ready-made talent pool, already versed in the airborne maritime domain awareness mission. Just as some P-3C and P-8A pilots, tactical coordinators, and sensor operators receive assignments to Unmanned Patrol Squadron 19 and execute Triton missions, a second unmanned patrol squadron could be established to oversee and direct HAPS UAV missions. After some initial successes, the Maritime Patrol and Reconnaissance Force could evolve into a triad of P-8As, MQ-4Cs, and HAPS aircraft, with tasking assigned or shared among the most appropriate of the three complementary and cooperative legs based on mission location, duration, and complexity.
Admiral Harry B. Harris, then commander of U.S. Pacific Command, testified before Congress in 2018 that the Indo-Pacific “presents a dynamic security environment requiring persistent and intrusive ISR” across a sweeping geographic area.18 A squadron of six to nine HAPS, launched and recovered in rural Australia on a phased cadence, would be ideally suited to providing such persistent and intrusive coverage across large portions of maritime Southeast Asia, while freeing human-crewed ships and aircraft from some of the operational burdens and risks of conducting FONOPs.
One national security think tank described the South China Sea as “an opaque, low-information” region suffering from a “dearth of situational awareness.”19 Solar-powered HAPS UAVs motoring through the stratosphere could gather insightful intelligence data promoting maritime transparency and freedom of navigation at a cost and fielding timeline Department of the Navy leaders should find compelling.
1. “Statement on United States Ocean Policy,” 10 March 1983, reaganlibrary.gov/archives/speech/statement-united-states-oceans-policy.
2. “DoD Annual Freedom of Navigation (FON) Reports,” policy.defense.gov/ousdp-offices/fon/.
3. Tuan Anh Luc, “From a Slow Simmer to a Boil: Managing Tensions in a Heating South China Sea,” The Diplomat, 16 October 2018, thediplomat.com/2018/10/from-a-slow-simmer-to-a-boil-managing-tensions-in-a-heating-south-china-sea/; ADM Scott Swift, USN (Ret.), remarks at CSIS South China Sea Conference, Washington, DC, 24 July 2019.
4. Laura Zhou, “Trump Signs Off on Plan to Allow U.S. Navy More Freedom to Patrol in South China Sea, Report Says,” South China Morning Post, 22 July 2017, scmp.com/news/china/diplomacy-defence/article/2103718/trump-signs-plan-allow-us-navy-more-freedom-patrol; Adam Smith, “Opening Statement (As Prepared) House Armed Services Committee Hearing on: The Fiscal Year 2021 National Defense Authorization Budget Request for the Department of the Navy,” 27 February 2020, armedservices.house.gov/hearings?ID=7D227481-B83D-4AE3-8A45-2D1406460126.
5. Airbus, “Airbus Zephyr Solar High Altitude Pseudo-Satellite Flies for Longer than Any Other Aircraft during Its Successful Maiden Flight,” 8 August 2018, airbus.com/newsroom/press-releases/en/2018/08/Airbus-Zephyr-Solar-High-Altitude-Pseudo-Satellite-flies-for-longer-than-any-other-aircraft.html.
6. Huw Williams, “Farnborough 2016: Airbus Releases Zephyr T Details, Outlines CONOPS for Systems,” Jane’s International Defence Review, 14 July 2016.
7. Andrew Chuter, “Airbus Marks Two Milestones for Zephyr Solar-powered Drone,” Defense News, 16 July 2018. defensenews.com/digital-show-dailies/farnborough/2018/07/16/airbus-marks-two-milestones-for-zephyr-solar-powered-drone/.
8. Anmar Frangoul, “BAE Buys British Firm Prismatic to Develop Solar-powered Drones,” CNBC, 11 September 2019, cnbc.com/2019/09/11/bae-buys-british-firm-prismatic-to-develop-solar-powered-drones.html..
9. Zenith Aerospace, “Tactical Services Tailored to Your Need,” zenithaero.com/.
10. Tim Kelly, “Exclusive: British Navy Warship Sails Near South China Sea Islands, Angering Beijing,” Reuters, 5 September 2018, reuters.com/article/us-britain-china-southchinasea-exclusive/exclusive-british-navy-warship-sails-near-south-china-sea-islands-angering-beijing-idUSKCN1LM017; Daniel Hurst, “South China Sea: Australian Warships Encounter Chinese Navy in Disputed Waters,” The Guardian, 23 July 2020, theguardian.com/world/2020/jul/23/south-china-sea-australian-warships-encounter-chinese-navy-in-disputed-
11. Airbus, “Airbus Celebrates Opening of the World’s First Zephyr Solar High Altitude Pseudo-Satellite Operating Site,” 3 December 2018, airbus.com/newsroom/press-releases/en/2018/12/Airbus-celebrates-opening-of-the-world-first-Zephyr-Solar-High-Altitude-Pseudo-Satellite-operating-site.html.
12. BAE, “Ground-breaking Solar Powered Unmanned Aircraft Makes First Flight,” 17 February 2020, baesystems.com/en/article/ground-breaking-solar-powered-unmanned-aircraft-makes-first-flight.
13. MAJs Edward P. Chatters IV, Bryan Eberhardt, and Michael S. Warner, USAF, “Orbital Mechanics,” in AU-18 Space Primer (Maxwell Air Force Base, AL: Air University Press, September 2009), www.airuniversity.af.edu/Portals/10/AUPress/Books/AU-18.PDF.
14. U.S. Department of State, “Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies,” https://2009-2017.state.gov/t/isn/5181.htm#treaty.
15. Minnie Chan, “How a Deadly Collision with a U.S. Spy Plane 18 Years Ago Brought Big Changes to China’s Air Force and Navy,” Business Insider, 4 April 2019, www.businessinsider.com/collision-with-us-spy-plane-near-hainan-causes-china-military-advances-2019-4.
16. Catherine Wong, “U.S., Chinese Warships within Metres of Collision in South China Sea, Leaked Pictures Show,” South China Morning Post, 3 October 2018, scmp.com/news/china/military/article/2166849/us-chinese-warships-within-metres-collision-south-china-sea.
17. Government Accountability Office, “DoD Acquisition Reform: Leadership Attention Needed to Effectively Implement Changes to Acquisition Oversight,” June 2019, gao.gov/assets/700/699527.pdf.
18. “Statement of Admiral Harry B. Harris Jr., U.S. Navy, Commander, U.S. Pacific Command, before the House Armed Services Committee on U.S. Pacific Command Posture,” 14 February 2018, docs.house.gov/meetings/AS/AS00/20180214/106847/HHRG-115-AS00-Wstate-HarrisJrH-20180214.pdf.
19. Mira Rapp-Hooper, Jeff Chism, Harry Krejsa, Paul Scharre, and Van Jackson, “Networked Transparency: Constructing a Common Operational Picture of the South China Sea,” Center for a New American Security, 21 March 2016, cnas.org/publications/reports/networked-transparency-constructing-a-common-operational-picture-of-the-south-china-sea.