Gray Zone Tactics Playbook: Going Dark

"Going dark" refers to the gray zone tactic of strategically turning off a vessel's Automatic Information System (AIS) transponder to avoid detection.
Miao Shou | AUGUST 17, 2023
Gray Zone Tactics Playbook: Going Dark
Vessels operating without AIS inside a country's Exclusive Economic Zone (EEZ). (Credits: Unseenlabs)

Miao Shou




"Going dark" refers to the gray zone tactic of turning off a vessel's Automatic Information System (AIS) transponder to avoid detection. AIS is a signaling system used to identify a vessel's type, position, course, speed and other navigation safety information, and is required by the International Maritime Organization for larger non-military ships operating in international waters. Read our primer on the AIS system here.
Going Dark in the Recent Water Cannon Incident

In a recent incident that involved the blockade and water-cannoning of a small Philippine resupply vessel and its escorts, six of the blockading ships were from the China Coast Guard. Of these, only one ship (CCG 5402) remained AIS-visible during the entire engagement, while two other ships (CCG 4203 and CCG 3302) broadcast AIS only intermittently. 

We can observe these periods of AIS-darkness from the dotted lines in the schematic below. 

AIS Data CCG Water Cannon.jpeg
Figure 1. CCG AIS data around Second Thomas Shoal on August 5, 2023.

The three other China Coast Guard ships documented by the Philippine Coast Guard as having taken part in the blockade--CCG 5201, 5304 and 5305--remained AIS-dark throughout the entire encounter. 

CCG 5304 arrived at China's military base at nearby Mischief Reef on 15 July with its AIS illuminated, and then patrolled the area for just over two weeks before moving east of Second Thomas Shoal. It then went dark near Sabina Shoal four days before the resupply mission.

The graphic below illustrates how 5304 went dark on 1 August, while the dashed line represents the fact that it was not detected again until it reappeared to the northwest 8 days later, after the resupply when it was well on its way back to Hainan Island. The period when it was in contact with the 5 August resupply mission is entirely missing from its AIS broadcast record.

Screenshot 2023-08-17 at 8.37.35 AM.png
Figure 2. CCG 5304 goes dark on 1 August

Meanwhile, CCG 5305 went dark on 30 July while still inbound to the Spratly Archipelago, nearly a week before the resupply mission. As of this writing nearly three weeks later the ship is still AIS-dark.

Screenshot 2023-08-17 at 8.46.30 AM.png
Figure 3. CCG 5305 goes dark 30 July

The last CCG ship involved in the 5 August blockade, number 5201, is a notoriously shadowy vessel which seldom turns on its AIS transmitter. Even when it does, it generally uses a bogus identification number (412000008) which it shares with dozens of other Chinese ships.

Though extreme weather conditions can hinder the transmission of AIS data, no such conditions were present on 5 August. These ships clearly either turned off their AIS transponders or switched from their stronger Class A transponders to weaker Class B signals to avoid detection and mask their activities. 

Dark operations and bright lasers

CCG ships frequently go dark when disrupting these Second Thomas Shoal resupply missions. On 6 February 2023, for example, CCG 5205 harassed the Phillippine Coast Guard ship BRP Malapascua while impeding its resupply escort mission using a bright green laser, or "dazzler".

As the Malapascua approached its rendezvous with the resupply boats near Sabina Shoal on the evening of 5 February, CCG 5205 headed into its path before going dark. It remained dark during the resupply on 6 February, when it was documented as the perpetrator in the laser incident.

Screenshot 2023-08-17 at 9.15.51 AM.png
Figure 4. CCG 5205 goes dark on 5 February
Feb 6 Laser.jpg
Figure 5. CCG 5205 uses "military-grade laser" against BRP Malapascua on 6 February 2023

Strategic illumination

Finally, some vessels play the dark operations tactic in reverse when they specifically want to be noticed. This is common in the oil and gas fields off Vietnam's southeastern coast. In these cases, we often see CCG ships turn on their transmitters while they patrol near Vanguard Bank, indicating that China is openly asserting its jurisdiction over these waters.

This example from July 2023 is typical. Below we see the world's largest coast guard ship, the 12,000-ton CCG 5901, illuminate its AIS on 3 July just before crossing into Vietnam's EEZ from the south. It then goes dark again on 6 July after completing its patrol, before moving off to the east.

Screenshot 2023-08-17 at 9.38.01 AM.png
Figure 6: CCG 5901 illuminates AIS specifically for its Vanguard Bank patrol.

See the rest of the playbook here.

Miao Shou

Miao Shou is a student at Stanford University, and a Defense Innovation Scholar at Stanford's Gordian Knot Center for National Security Innovation.

More Articles

Gray Zone Tactics Playbook: Pretext to Escalate
While other countries treat maritime incidents as crises to be deescalated, Beijing seizes upon them as pretext for calculated escalations, by which it means to reset the board in its favor.
It's time for U.S. troops to visit Thitu Island
The U.S. has long kept its distance from the occupied South China Sea features, holding to the notion that keeping the status quo was crucial to avoiding conflict. Unfortunately, Beijing interpreted this reticence as weakness and gutted that status quo, while America's treaty ally, the Philippines, bore the brunt of China's gray-zone expansionism. The journey toward reclaiming the initiative can start with a single, modest step--sending U.S. & Philippine military doctors and engineers to Thitu Island.
Infographic: Chinese Provocations in the South China Sea
A quick-reference guide to South China Sea hotspots.
sealight logo
Contact Us