According to a study by Stable Seas, illicit actors are exploiting instability in Yemen’s maritime environment exacerbated by the ongoing civil war. This breach in maritime security has been made more acute because of damage to the country’s infrastructure, including a substantial portion of the facilities supporting Yemen’s maritime industry. Naval installations and two professional military education (PME) institutions — the Naval Institute and Naval School — were damaged during the conflict. As a consequence of the civil war, Yemen faces limited maritime resources and institutional capacity to police its waters and counter the rise of maritime crime. While Yemen’s maritime challenges cannot be comprehensively addressed until the conflict is resolved, there are strategies that can help allocate resources toward mitigating security gaps. Data can provide a strategic framework for addressing Yemen’s maritime security challenges while also strengthening partnerships and improving maritime domain awareness in the wider Red Sea Region. Specifically, data is an instrument for addressing three security challenges: maritime enforcement, coastal welfare, and rule of law.
Maritime Enforcement
Maritime enforcement can be made more effective by implementing a system of maritime monitoring. This system would collect and report data on what is happening within Yemen’s territorial waters, especially what types of threats are present and what trends exist. Maritime data reveals patterns that can help human operators recognize anomalies. A more comprehensive picture built from this data would also assist policymakers in mapping an adequate response. Yemen does not have the ability at present to dispatch vessels to monitor its waters at sufficient scale. Adaptation is necessary, and data can provide a path forward for generating new insights into maritime insecurity. It is true that before a data-driven approach is adopted, a system of data collection must be built. Although it would take time to implement such a system, a data-driven strategy is a clear pathway for long-term investment into the country’s security and development that is also feasible within the constraints of the larger political environment of the civil war.
Consider the example of arms trafficking. Type 56-1 rifles are a prominent weapon documented in Yemen and Somalia with strong evidence suggesting Iranian origins. These weapons are transported via dynamic maritime trafficking networks. To complicate matters further, the total travel time for a small vessel between Yemen and its coastal neighbors is only a few hours. This means law enforcement must respond quickly, which is only possible when supported by real-time monitoring. Moreover, collecting data and mapping the location of interdictions or other maritime incidents may help predict future smuggling patterns, which would empower law enforcement to be more precise in how they orchestrate patrols or plan interceptions. Yemen will not stop smuggling in its waters, but it can raise the stakes for criminal actors and increase the cost of their illegality.
The scale of information can also be increased when other actors agree to share maritime data, such as Combined Maritime Forces in Bahrain, regional states, and active non-regional states and actors. If Yemen presents a willingness to use data more routinely, then it may incentivize neighboring partners to participate in information-sharing. The relationship between data and cooperation is cyclic — as more data is collected and shared, states are better informed about possible security threats. A more informed response has a greater likelihood of success, which provides policymakers with more intelligence about illicit activities at sea, thereby encouraging more partnerships.
Coastal Welfare
Maritime domain awareness, enhanced through data collection and monitoring, can improve coastal welfare insecurity. Based on the definition provided by Stable Seas, coastal welfare encompasses the “physical and economic wellbeing” of coastal communities, including the health of local fisheries. Specifically, there exists a relationship between the fishing industry in poor coastal areas and criminality. An increase in piracy often follows an increase in unemployment among individuals employed by coastal industries. Extremist groups and pirates may recruit local fishermen for their navigation skills, and a struggling fishing industry may make local communities more susceptible to joining criminal organizations. Piracy and other forms of violent criminal conduct are correlated with illegal and unreported fishing, which not only damages local marine ecology, but threatens the livelihoods of coastal communities. Yemen’s coastal communities have been grossly impacted by the civil conflict, and the subsequent loss of income and labor stability equates to an environment where many turn toward illegal activities.
A free and easily accessible source of data to highlight in the case of coastal welfare is the visible infrared imaging radiometer suite (VIIRS). VIIRS data captures the location of maritime activity at night and can be a mechanism by which to better enhance maritime domain awareness. Such data may be collected to identify clusters of maritime activity and enhance management of fishing resources and suspected smuggling.
Rule of Law
Finally, a data-driven approach to maritime security has institutional implications that could bolster rule of law. Many of the advantages of data lay in the process by which it is analyzed and communicated to internal and external partners. Maritime professionals need to be trained in different aspects of data management, and teams of analysts need to be employed to evaluate policies based on empirical evidence. Various branches of Yemeni law enforcement will be able to communicate faster and more effectively, increasing Yemen’s institutional capacity to police its waters and develop new solutions to emerging threats. The costs of integrating a more data-driven approach are initially structural in nature, as it requires the retooling of the workforce. Financial costs, while a burden, are not insurmountable given the expansion of commercial firms, applications, and free data. With international assistance also becoming more common, such as through the U.S. SeaVision and EU IORIS systems, the financial burden becomes less prohibitive.
Expanding information sharing could become the basis for intensified institutional cooperation in the region. Despite the challenges it faces, Yemen remains an active member of the maritime community in the Red Sea and Indian Ocean Region. Yemeni coast guard and port security officials routinely engage in training platforms and educational forums with their immediate neighbors, the European Union, and the United States, among others. Partner efforts should not only prioritize technical training for Yemeni maritime professionals, but also actively provide analysis premised upon their own maritime data.
Existing Technology
Data collection and processing applications already exist in the public realm, as do open-source datasets. Yemen does not need a cohort of technological experts to utilize these applications and deliver improved assessments. The applications that process data also assist in the analysis. Combined with active assistance from partners, Yemen could significantly improve its access to and analysis of a large amount of information. Platforms such as ArcGIS and QGIS are relatively easy to use and support various kinds of data mapping. Other platforms report data on the maritime domain, such as Global Fishing Watch, National Geospatial Intelligence Agency Anti-Shipping Activity Messages database, and Esri’s ArcGIS online repository of public data. These platforms often report maritime data as CSV, geoJSON, shapefiles, or other formats that can be imported into a mapping software and visualized. Outside of mapping software, other open-source software such as Python and R contain numerous packages for importing and mapping data.
Conclusion
Data has the potential to be a central pillar of maritime security in Yemen and maritime domain awareness in the wider Red Sea Region. The transnational nature of maritime security necessitates a cooperative enterprise where data is requested and shared among state actors. Regional pursuits for maritime domain awareness depend on lowering the barriers between state actors, which the collection and sharing of data will help stimulate. Because data can be easily shared, it is an asset in building a stronger maritime community through a collective understanding of challenges. Therefore, Yemen should intensify its use of maritime data and request assistance in doing so, while partner nations with greater capability should provide as much assistance as possible. This will build trust and provide a clear collaborative framework for securing the greater Red Sea Region.
Jeffrey Payne is a Professor at the Near East South Asia (NESA) Center for Strategic Studies in Washington, DC.
William Thompson is a graduate student at the University of Cincinnati. The views expressed in this article belong to the authors and do not represent the official policy or position of the NESA Center or the U.S. Government.
Featured image: Yemen coast guard vessels patrol the waters near Mukalla, Yemen, on November 29, 2018 (Credit: AP Photo/Jon Gambrell)
In 2004, two US Navy personnel and one member of the Coast Guard were killed in a blast while attempting to board a boat near the Khawr Al Amaya oil terminal off Basra. Two other explosive-laden watercraft detonated nearby, though they did not cause any casualties. The attacks were later claimed by Abu Musab al-Zarqawi, the leader of Al-Qaeda in Iraq (AQI) at the time and the founding father of the Islamic State (IS) movement. Notably, the statement drew a comparison to the 2000 USS Cole bombing in Yemen, demonstrating AQI’s historical knowledge of jihadi attacks by sea and their strategic consciousness about the insurgent opportunities inherent to the maritime domain. Additionally, the statement threatened a continuance of attacks by sea, land, and air “until victory or defeat.” AQI would make good on this promise the following year, firing rockets at the Jordanian port of Aqaba and Israeli port of Eilat.
These maritime attacks were also bolstered by AQI’s river-based movements and knowledge. The historian Kimberly Kagan describes how, during the 2007 surge, AQI (then called Islamic State in Iraq) “operated almost freely in a pendulum-like arc south of Baghdad, swinging from the Euphrates to the Tigris,” adding that “they traveled southeast along the Euphrates River, often by boat, from Fallujah to Sadr al Yusufiya.”
This mode of maritime activity by IS’s organizational predecessor would continueand ultimately expand under the Islamic State. IS has proven highly adaptable and, accordingly, has sought to use geography to its advantage. In the case of Iraq and Syria, the networks have long operated along the coasts and throughout the region’s river systems. IS has traditionally exploited the maritime domain for its kinetic operations, for propaganda purposes, and, in some cases, to raise funds. To be sure, the IS movement is a primarily land-centric phenomenon, yet the propensity for maritime operations is deeply ingrained into its organizational DNA.
A screenshot portrays a group of IS fighters (Credit: Terrormonitor.com)
The Islamic State has historically been quite active along the Euphrates and Tigris, traversing throughout to move fighters, weapons, explosives, and supplies; conduct reconnaissance; prepare for and launchattacks; and strike using gunboats and boat-borne IEDs. The rivers have allowed IS fighters to avoid roads, checkpoints, and bridges. In fact, IS has even blown up such structures, including a bridge connecting Dhulueya and Balad using explosive-laden watercraft.
The Islamic State’s use of river systems was so prevalent during its high period that anti-coalition forces conducted intense airstrikes against jihadis travelling by boat. One report from 2016 stated the US and its allies had sunk over 100 IS boats up to that point, with 65 of them destroyed in a single month. The group has used barges, motorboats, and rowboats to travel around the area.
IS fishing propaganda (Credit: Weddady).
The Islamic State’s military strategy includes a significant media warfare component, and some part of this has been leveraged to weaponize the maritime domain. The Islamic State movement was early to recognize the US Navy as central to American power projection, with IS spokesman Abu Muhammad al-Adnani boasting that “Allah’s law” is “being implemented despite” the opposing military coalition’s “legions, arsenals, planes, tanks, missiles, aircraft carriers, and weapons of mass destruction.”
Further solidifying this weaponization of the maritime domain, another IS figure lamented in March 2015 that “today, Worshippers of the Cross and the infidels pollute our seas with their warships, boats, and aircraft carriers and gobble up our wealth and kill us from the sea.” The group’s supporters responded to this statement with optimism, saying IS will “take to the sea in what is only a matter of a short time,” forecasting the “creation of an Islamic fleet by the Islamic State,” and saying that an IS navy would aim to sink “warships and [commercial] ships… and to threaten their shores and lines of communication… an entire fleet, God willing, not just a single ship.”
For the Islamic State, the seas have also been viewed as a way to infiltrate the soft underbelly of Europe and to attack and invade its enemies in the West. One propagandist suggested that a Mediterranean maritime presence could “bring us closer to conquering Rome sooner rather than later.”
In a particularly notable video intended to show off the skills of its forces, fighters flaunted their amphibious capabilities by swimming in the Tigris and maneuvering in small boats.
Aside from threats, IS’s propaganda apparatus has produced photos and videos of militants paddling, fishing, selling their catches at local markets, and even scuba diving — such imagery was intended to show the serenity of life in the caliphate and the high spirits of the Islamic State’s rank and file.
Another IS fishing propaganda photo (Credit: Terrormonitor.com)
However, some of this activity served more practical purposes. As the Islamic State’s caliphate territory was rolled back by the US-led military coalition, the organization exploited the fishing industry as a source of funding. In 2016, Reuters reported about how the group turned to farming and selling fish in Iraq to finance their operations. It should be noted, though, that the Islamic State and its previous iterations had reportedly been involved in the industry since at least 2007 when AQI was fighting the Americans following their 2003 invasion.
IS-associated militants on a boat in the Lake Chad region (credit: Evan Kohlmann).
Even with the loss of land control in Iraq and Syria, IS guerrillas continue to operate along the region’s river systems. And with the organization’s international expansion and the establishment of a global network of insurgent hubs, the group’s branches, from the Sulu-Celebes Sea to the Lake Chad Basin, are more actively incorporating maritime activities into their insurgency campaigns.
Lucas Webber is a researcher focused on geopolitics and violent non-state actors. He is cofounder editor at militantwire.com and writes a newsletter at sinosecurity.org. You can find him on Twitter: @LucasADWebber
Featured Image: Islamic State video portrays Islamic State fighters using boats to cross the Euphrates (credit: Oryx).
Today, Chinese underwater gliders operate throughout the Indo-Pacific, from the Bay of Bengal to the Bering Sea, fromhigh seas to sovereign waters. These winged, torpedo-like submersibles are being deployed in droves to collect information about the marine environment. Traveling underwater in a vertical sawtooth pattern, gliders use onboard sensors to measure characteristics of the ocean such as temperature, salinity, dissolved oxygen, and current speed at different depths to generate water column profiles. This data indirectly bolsters the capabilities of the People’s Liberation Army Navy (PLAN) by expanding its tactical understanding of the ocean environment.
Scientists and engineers based in the People’s Republic of China (PRC) are also developing a new generation of gliders that could play a far more direct role in naval combat by detecting enemy submarines. Since 2014, experts at the PLAN Submarine Academy, working with colleagues at civilian institutions, have been equipping Chinese gliders with passive acoustic sensors. Chinese language records of their activities show a determined effort to adapt this technology for anti-submarine warfare (ASW), an enduring weakness for the PLAN—one that, if remedied, could shake U.S. conventional deterrence in the Western Pacific.
Why Gliders?
The PLAN has a very difficult time detecting advanced foreign submarines within Chinese-claimed maritime space. Modern submarines are stealthy, the ocean is vast and complex, and ASW is inherently difficult—for any navy. But the stakes are especially high for China, given the perceived threat that foreign submarines pose to China’s maritime security. PRC experts often lament that China’s “underwater front door is wide open” (水下国门洞开). China’s 13th Five Year Plan for Innovation in Marine Science and Technology frankly admittedthat China “still lacks the ability to resist hostile threats from the deep sea.” One PLAN analyst declared, “the threats our country faces in the maritime direction mainly come from the undersea [domain], and the main gap with the powerful enemy [the U.S.] is also in the undersea [domain].”
To shrink this capability gap, the PRC has invested heavily in new ASW capabilities for its fleet while looking to the U.S. Navy as a model. The PLAN has built ocean surveillance vessels like the USNS Effective to tow acoustic sensors designed to detect submarines. The PLAN has also procured sub-hunting maritime patrol aircraft, similar to the U.S. Navy’s P-3 “Orion,” and it may soon begin equipping the fleet with an ASW variant of the Z-20 helicopter, often described as a close copy of the MH-60 “Seahawk.”
The PRC is also taking steps to build a network of sensors, some mobile and some fixed, to detect foreign submarines in operationally important areas. Together, these sensors would constitute an “undersea alert system” (水下警戒体系). Some ASW platforms use traditional hydrophones, which only capture information about the frequency (hertz) and intensity (decibels) of sound. However, to localize the source of the sound, multiple hydrophones are often combined into an array, which can be large and unwieldy. A single vector sensor, in contrast, is capable of determining the direction of a sound source. China is very keen on pursuing a new generation of piezoelectric vector sensors, which are far smaller than previous types. Their compact size also allows their installation on much smaller platforms like underwater gliders.
Gliders move up and down in the water column by adjusting their buoyancy while their “wings” enable them to move forward at an angle. As ASW platforms, gliders offer several advantages. Due to their low power requirements, some gliders can operate at sea for months at a time. Because of the simplicity of their design, gliders are also comparatively cheap—an important attribute since they must be deployed in large numbers to be effective. Unlike fixed undersea sensors, gliders can move to where they are needed (albeit very slowly, at just about one knot). Lastly, gliders can maintain regular communications with their operators by transmitting their location (and other information) and receiving new commands when they surface at the end of a dive.
How might the PLAN use acoustic gliders? According to the PLAN researchers working on the project discussed in this article, they would be used to “complete tasks such as autonomous detection, tracking, attribute discrimination, and sending back information on moving targets in sensitive waters or areas of denial (拒止区域).” The program director, Rear Admiral Da Lianglong, likened them to a front-door “security system” (安保系统). One of his briefing slidesfrom a 2019 presentation suggests that the PLAN intends to deploy them in the relatively quiet, deeper waters of the Philippine Sea and northern South China Sea, operationally-important areas where China lacks islands to build fixed undersea arrays.
Rear Admiral Da Lianglong with colleagues at the PLAN Submarine Academy (Source: 81.cn)
The Dolphin Project
While the advantages of gliders seem obvious, there are also many technical challenges that must be overcome before they can be used in ASW. Since 2014, the PLAN Submarine Academy, working in conjunction with scientists and engineers from Tianjin University and the Qingdao Pilot National Lab for Marine Science and Technology have methodically surmounted many of these challenges and now possess a capable prototype glider, the “Dolphin,” which has already undergone several rounds of testing in the South China Sea.
The Dolphin is based on the Haiyan glider developed by researchers at Tianjin University. Like most sea gliders, the Haiyan is a tubular robot with wings and a visible antenna. However, it is somewhat unusual in that it is equipped with a small propeller, a useful feature if needed to surface quickly in the event of a potential submarine contact. Chinese oceanographers have already deployed Haiyan gliders within the first island chain and beyond. A specially designed Haiyan variant (Haiyan-X) is capable of diving to tremendous depths, including the bottom of the Mariana Trench. Another variant (Haiyan-L) has been built for greater endurance, purportedly up to five months of continuous operations.
The Dolphinlooks likea typical Haiyan glider, except for a vector sensor protruding from its nose. Within the body of the glider, forward of the batteries, is its signal processor. indicating that the platform is designed to autonomously detect, classify, and locate undersea targets, not merely to record and transmit raw data for interpretation elsewhere.
The Dolphin project is led by the Naval Undersea Warfare Environmental Research Institute(海军水下作战环境研究所) at the PLAN Submarine Academy. It is overseen by the Institute’s Director, Rear Admiral Da Lianglong, perhaps the PLAN’s most accomplished expert on undersea science and technology. Rear Admiral Da has won numerous national, provincial, and military awards for his work on how the undersea environment affects sonar performance and submarine tactics.
Under Rear Admiral Da’s leadership, the Environmental Research Institute has shrewdly leveraged civilian organizations to help advance its mission. In 2013, his institute turned its attention tovector sensors. Then, in 2016, it joined with the Qingdao Pilot National Lab for Marine Science and Technology to create the Joint Lab for Civil Military Integration in Qingdao, with Rear Admiral Da as its director. This allows the Submarine Academy to benefit from the expertise, access, and resources available to the civilian marine science community. When Xi Jinping visited the Qingdao Pilot National Lab in June 2018, he spoke about the importance of civil-military integration in marine science. Rear Admiral Da stood beaming in the audience, the embodiment of Xi’s ideal.
Milestones
The team at the Submarine Academy overcame several technical challenges to make the Dolphin a viable ASW platform including self-noise, contact localization fidelity, and overcoming the immense pressure water pressure of deep dives.
The first was self-noise. Researchers originally built the Haiyan glider for oceanographic research, where self-noise is far less of a concern. However, when detecting submarines, it is vital that an ASW platform be as quiet as possible to make it easier to distinguish the relevant signatures from other noises and thereby maximizing the signal to noise ratio. This is especially important when that signature is extremely faint, like those emitted by modern submarines.
The Haiyan produces noise at the bottom of its dive, when a pump activates to increase buoyancy needed for the ascent. It also produces noise when the propeller engages. These noise problems, however, are simple fixes since the glider can be programmed to turn off its vector sensor during the brief periods when the pump and propeller are on. For the Chinese researchers, the real challenge was reducing the noise generated by the mechanisms used to maintain the glider’s course and attitude. Researched overcame this challenge by changing the position of the glider’s internal battery packs. Through a series of tests conducted at first in specially designed pools followed later by tests in the South China Sea, the researchers were able to optimize attitude and course adjustment mechanisms to reduce this self-noise.
Slight changes to the attitude of the glider presented a second challenge that had to be overcome: errant localization. The vector sensor receives data about the direction of a target in relationship to the attitude of the sensor at the time of detection. For this information to be tactically valuable, the glider required a tiny attitude sensor that would enable an onboard computer to locate the target relative to the surface of the ocean. Scientists at the PLAN Submarine Academy, including Da Lianglong himself, successfully developed a sensor for this purpose and it now equips the Dolphin glider.
Attitude sensor developed for the Dolphin (Source: KNS.CNKI ).
Finally, Chinese scientists also had to develop a vector sensor that could reliably operate in the high-pressure environment of the deep ocean. Since many countries prohibit the sale of acoustic sensors to China, researchers could not simply import a foreign product. Since the early 2000s, experts at Harbin Engineering University have conducted pathbreaking researchon vector sensors. The team at the Submarine Academy built off their work to develop a deep water vector sensor. In 2019, researchers tested the new sensor in the South China Sea at depths of 800 meters and 1,200 meters with promising results. That same year, Rear Admiral Da and several other colleagues at the Submarine Academy patented a vector sensor that could effectively operate down to 4,000 meters. According to their patent application, the sensor could be particularly suited for unmanned platforms like gliders “for use in submarine detection.”
Deep water vector sensor developed for the Dolphin (Source: KNS.CNKI)
Since 2018, the Dolphin has undergone multiple tests in the South China Sea, in the deep water northwest of the Paracel Islands. To date, Chinese researchers have only tested the glider’s ability to detect surface ships, which are obviously much louder than submarines. Two series of tests conducted in May and June of 2018 focused on reducing self-noise. Since then, the team has sought to refine the capabilities of the glider’s onboard systems. The most recent known tests conducted in January of 2020 offer a gauge of the Dolphin’s current capabilities. They also show the scale of the PLAN’s commitment to developing these platforms.
During the January 2020 tests, a Dolphin glider successfully tracked the movements of a 50 meter research ship (Haili) traveling at 8 knots at a maximum range of 6.5 km. As part of the same series of tests, a Dolphin glider also tracked a 60-meter merchant ship traveling at 11.7 knots at a maximum range of 11.4 km. The Dolphin also tracked the movements of a 192-meter container ship traveling at 15 knots at a maximum range of 11.2 km. Additionally, in January of 2020, a Dolphin glider tracked a 99-meter rescue and salvage ship, the Nanhaijiu 116, steaming at 14 knots at a maximum detection range of 14.4 km.
Next Steps
To be effective, a glider like the Dolphin would need to work in concert with other such platforms. A single glider would not be enough, since detection ranges will be very short and gliders are not very mobile. The PLAN will likely want to fill an operationally important area of the ocean with dozens of gliders, which will need to be coordinated to ensure efficient coverage. This will be further complicated by the fact that gliders, due to their slow speeds, are vulnerable to undersea and surface currents. Therefore, if one glider drifts out of a given area, another glider will need to move in to fill the gap. Researchers at the Submarine Academy and the Qingdao Pilot National Lab already completed simulations to address the challenge of optimizing the deployment of multiple gliders for target detection. However, these efforts have not yet been tested at sea.
Another challenge is autonomy in signal processing. Gliders will need to analyze the raw acoustic data they receive and determine if what they are “hearing” contains the signature of a target of interest. That task is fairly easy if the target is a 190-meter commercial ship traveling at 12 knots. But it becomes extremely difficult when it is a modern submarine operating at slow speed in the noisy waters of the South China Sea. Detecting and classifying targets has traditionally required humans (i.e., sonar technicians) in the loop. Developing systems that can mimic human intelligence will be vital for any autonomous ASW platform, and Chinese experts have been working on this problem for years, again, most notably at the Harbin University of Engineering. Researchers there claim they have developed unmanned platforms capable of autonomously detecting surface and undersea targets at long range and have tested them in lakes and at sea. In October 2018, the University signed a cooperative agreement with the Submarine Academy, although it remains uncertain if this will include collaboration on underwater gliders. In the meantime, researchers from the PLAN Submarine Academy and the Qingdao Pilot National Lab are proceeding with their own efforts to improve autonomy in target detection.
This relates to another huge challenge of filtering out false detections. Failing to detect an enemy submarine is bad, but declaring the presence of an enemy submarine where none exists could be potentially worse for the PLAN. It might deploy manned ASW assets to the area of false contact, wasting time and resources. Acoustic gliders will likely not be deployed for real-world operations until the PLAN is reasonably certain that onboard systems are sophisticated enough to keep false detections to an absolute minimum. In this situation, redundancy in the undersea alert system (i.e., many sensors in a given area) could help strengthen confidence in a target detection.
Conclusion
Writing in early 2013, before substantive work on acoustic gliders began in China, an expert at the 710 Research Institute boldly predicted—in his words, “without the least bit of exaggeration”—that the future development of underwater gliders would leave submarines with “no place to hide” (无处遁形). Almost ten years later, the PRC is still nowhere close to that. However, the PLAN has come a long way in a short period of time. This achievement has been made possible through a talented, dedicated, and well-funded research team at the PLAN Submarine Academy, a successful approach to civil-military integration, and institutional commitment to redressing China’s weaknesses in ASW. China now possesses a viable prototype acoustic glider that has undergone multiple rounds of testing in the South China Sea. China clearly intends to shut its “underwater front door,” and acoustic gliders will be one tool that helps it do just that.
Ryan D. Martinson is a researcher in the China Maritime Studies Institute at the Naval War College. He holds a master’s degree from the Fletcher School of Law and Diplomacy at Tufts University and a bachelor’s of science from Union College. Martinson has also studied at Fudan University, the Beijing Language and Culture University, and the Hopkins-Nanjing Center.
Featured Image: The guided-missile frigate Zhoushan (Hull 529), together with the guided-missile destroyers Taizhou (Hull 138) and Hangzhou (Hull 136), steam to designated sea area in East China Sea during a maritime training exercise in early January, 2021. (eng.chinamil.com.cn/Photo by Liu Yaxun)
