Why would a secretive Chinese research vessel hover for days over a sensitive undersea cable in Palau’s territory, while not answering Palau’s radio calls?
In part 1 of this article we looked at the two known types of over the horizon radar (OTHR). The U.S. announced recently that it was building an OTHR on the islands of Palau, which lie between the Philippines and the strategic U.S. military bases on Guam.
To keep its enemies guessing, the Pentagon did not say whether this facility will be a “backscatter” or “surface wave” version of OTHR. Backscatter OTHR can see over the horizon because it pulses radar waves upward and bounces them off the Earth’s ionosphere, from where the radar waves travel back down to Earth, allowing the radar to sense surface objects as far away as 3,500 kilometers.
Surface-wave OTHR, on the other hand, pulses radar waves horizontally over the ocean, where the conductivity of the ocean surface allows the wave to travel around the curve of the planet. This latter type of OTHR has a shorter range of around 500 kilometers, but it does give a clearer picture of what is happening over the horizon compared to backscatter OTHR.
Normal radar is more powerful than OTHR, but can’t sense near-surface objects past the horizon, which is only 5 kilometers away when viewed from 2 meters above sea level. However, whereas normal radar is accurate enough to provide effective targeting information to guided missiles, OTHR can only give a general idea of the location, direction and speed of target platforms like warships, airplanes and missiles. For that reason, OTHR is generally considered to not be a targeting system but rather an early-warning tool to give defenders domain awareness and an idea of where to aim their missiles and radars.
When we look at Palau’s position on the globe, we can see that a surface-wave OTHR with a maximum range of 500 kilometers would only give coverage of the ocean around Palau and would not be able to provide Guam with early warning of near-surface attacks coming from the Chinese mainland. However, backscatter OTHR with a maximum range of 3,500 kilometers would be able to scan surface objects as far away as Tongren City in Guizhou province on the Chinese mainland — 900 kilometers beyond the Chinese coastline.
A Mysterious Ship
The Palau government said on May 30 that a Chinese research vessel had entered Palau’s exclusive economic zone without providing any notification on the afternoon of May 24. “It slowed to about one to two knots as it passed over Palau’s fiber optic cable. It continued with questionable maneuvers, passing about 45 nautical miles from Kayangel [Palau’s northernmost atoll],” according to Palau’s National Security Coordinator Jennifer Anson. Anson added that attempts by Palau’s Joint Operation Center to contact the vessel via VHF radio were unsuccessful.
International law states that nations have exclusive rights to economic exploitation of a 200-nautical mile zone around their land borders, called the exclusive economic zone (EEZ). The seas beyond 12 nautical miles are international waters, so foreign vessels can pass through them, but unnotified research vessel activity in the EEZ could be perceived as a security or economic threat.
Palau said bad weather made it impossible for its maritime security force to deploy its patrol boat and aircraft at the time. By May 29, five days after the vessel started snooping around the undersea cable, the ship was seen heading toward Micronesia.
The incident raised the question of why a Chinese ship would be hovering for days over an undersea cable that connects Palau to Guam and the rest of the world. Apart from sensitive information that would be flowing between Palau and allies like the U.S., the cable also represents the fastest and most dependable way for the new OTHR installation to send early-warning and domain-awareness data to the large U.S. military bases on Guam. If the research vessel did indeed interact with the cable, it could have gathered data about the exact position of the cable for later use, or it could have tampered with the cable directly.
This tampering could have been in the form of tapping the cable, or installing a device that could start tapping the cable at a later date. During the Cold War, the tapping of undersea cables was relatively simple, as the low-capacity cables of that era were designed around simple copper cores. Modern undersea internet cables are designed around multiple fiber-optic strands that are each only as wide as a hair but can pulse data in the form of light waves, which means they can pulse enormous amounts of data at the speed of light.
These days it is important for governments to control their corporations’ private undersea internet cables, and nations don’t want their cables to make landfall on the territories of non-allies. At the heart of the issue is the fact that it is too easy for a nation to “tap” modern fiber-optic cables that make landfall on its territory. Due to the complex and fragile nature of fiber-optic cables, it is still extremely hard to tap optical cables on the seabed, though the U.S. hinted in 2005 that it managed to do just that with one of its most sophisticated spy submarines.
If the Chinese research ship did indeed try to tap Palau’s data cable — which is a spur cable that connects Palau with the region’s main undersea cable that lies 110 kilometers to the northwest — it would have to lower divers and some kind of chamber to the seabed. The ship in question, the Haiyang Dizhi Liuhao, is a large research vessel equipped with multiple cranes, so it would be capable of lowering a relatively large chamber. In theory, such a ship could lower a chamber over an undersea cable, where personnel inside the chamber could then conceivably tap the cable or attach equipment to the cable that could “mirror” all data flow toward a nearby recording device that could then transmit the mirrored data to a faraway listening post.
Alternatively, it is possible that a device spliced into the cable could be used to intercept real data and transmit fake data. Thus, in the future, it could be used to send data that pretends to be data from the OTHR on Palau to U.S. military installations on Guam. Such hypothetical fake data could be intended to trick the U.S. military into thinking a real attack is not happening, or that a fake event is happening.
Of course, it is possible that the Haiyang Dizhi Liuhao just accidentally hovered for days over a spot that just happens to be where Palau’s undersea cable passes underneath. It is also possible that the ship just accidentally did so during rough weather while accidentally not answering radio calls from Palau’s maritime authorities. However, it is understandable that Palau and the U.S. would be very suspicious about the incident, and it is conceivable that both sides would want to take a very close look at the part of the cable and the surrounding seafloor where the ship lingered.
Image: Luka Peternel, CC BY-SA 4.0
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