Did a Chinese-owned Dredger Spy on U.S. Military Operations in the Philippines?
In December 2024, the Philippine Coast Guard (PCG) conducted an inspection of An Da Kang 3689, a Chinese-owned, Philippine-flagged dredging vessel, off the coast of western Luzon. According to a report by the Philippine Daily Inquirer, the vessel had previously exhibited suspicious activities, including deactivating its Automatic Identification System (AIS), making unexplained route deviations, and conducting offshore maneuvers near American military deployments in Northern Luzon. During the inspection, six Chinese crew members were found aboard, all with valid licenses, and no irregularities were identified at that time.
In the months before this incident, I was first tipped off to An Da Kang 3689's irregular pattern of operations by a source who prefers to remain anonymous. Working in collaboration with a small group of regional and maritime analysts, we examined AIS and satellite imagery data to better understand what the vessel had been doing. We shared our findings (consisting in part of the figures shown below) with the U.S. and Philippine governments in the fall of 2024, which seems likely to have prompted the inspection by the Philippine Coast Guard discussed above.
So, what was the basis of our suspicions? An Da Kang had previously operated on a consistent sand-hauling route between Manila and the western coast of Luzon, primarily to San Felipe and San Narciso. As shown in Figure 1, before March 2024 the vessel maintained this corridor without any significant deviation.
That changed on 21 March. As seen in Figure 2, An Da Kang 3689 departed its usual route and proceeded north to the coast of Laoag. There it remained in close proximity to the Laoag International Airport for over two weeks.
On 14 April, the ship departed Laoag and Philippine waters, for unknown reasons heading hundreds of miles northwest across the South China Sea. Figure 3 shows that on 15 April, the vessel came to a near-stop off about 130 nautical miles from the Chinese coastline and loitered before turning around and returning to Philippine waters.
AIS data (see Figure 4) shows that around the time it slowed down, An Da Kang altered its broadcast to a Panamanian flag and transmitted a different callsign - a red flag indicating a likely intent to obfuscate its operations. Over the course of several hours, at least eight Chinese and Taiwanese fishing vessels passed nearby, although no physical rendezvous can be confirmed.
An Da Kang returned to Laoag on 17 April. As shown in Figure 5, it subsequently transited to the coast off Port Irene by 3 May. AIS coverage in this area was limited, but the available data shows no discernible dredging activity.
What drew our interest from all of this data was that An Da Kang’s movements seemed to anticipate key U.S. military deployments in the Philippines. This suspicious was heightened significantly by the unexplained partial-voyage toward China, and the seemingly-deliberate obfuscation of its AIS transmissions during a time when it may have been conducting a rendezvous.
As depicted in Figure 6, the U.S. Army’s 1st Multi-Domain Task Force arrived in the region on 8 April and deployed the Typhon missile system to Laoag. By 20 April, two Typhon launchers were visible on the tarmac at Laoag International Airport.
Figure 7 outlines later movements of U.S. HIMARS systems in early May. One launcher was flown by C-130 to La-Lo on 6 May and conducted simulated fires. On 7 May, the system convoyed overland to Port Irene—a movement bracketed by An Da Kang 3689's AIS blackout and maneuvering offshore.
Figure 8 summarizes this timeline, showing how the vessel’s unexplained repositioning seemingly anticipated the arrival and transit of U.S. military assets.
In the months following the December 2024 inspection, An Da Kang came under renewed scrutiny in March 2025, when a joint Philippine Coast Guard and MARINA inspection found nine Chinese nationals working aboard. This time, their presence violated crewing regulations that restrict foreign workers to advisory roles within Zambales. This regulatory breach alone does not imply intelligence activity, but it adds to a pattern of irregular behavior. Philippine Star coverage of this inspection can be found here.
After the December 2024 inspection, An Da Kang’s operational behavior has returned to a more routine pattern, perhaps because—if it had been used to collect intelligence—its cover was now blown.
The case of An Da Kang is emblematic of broader challenges posed by China’s civil-military fusion strategy, which encourages commercial and civilian entities to support national defense objectives. The U.S. Department of Defense's designation of the shipping giant COSCO as a Chinese military company illustrates how Chinese commercial actors can serve strategic functions under this model.
In the end, several key questions remain unanswered. Did An Da Kang actually collect intelligence on U.S. military operations, or was this some sort of extreme set of coincidences? (This seems highly unlikely to me.) What was the result of the initial Philippine inspection of An Da Kang 3689 in December 2024, and why was the vessel and its crew released? Why is the vessel still being allowed to operate in Philippine waters? If An Da Kang 3689 in fact was conducting surveillance of U.S. military operations in the Philippines, what information might it have collected? More broadly, are other PRC-owned and -operated commercial vessels being used to surveil U.S. and allied military activities in the region? And of course, did the PRC have foreknowledge of U.S. military movements in the Philippines? If so, how did it get it?
With continued U.S.-Philippine cooperation in the Philippines, activity by Chinese-owned vessels in these waters demands close monitoring. More broadly, An Da Kang 3689 is not the only commercial Chinese vessel that raises concerns. While this case remains unusual, the broader presence of Chinese state-owned commercial ships operating in and around sensitive locations in the Philippines and elsewhere—such as in or near U.S. ports and naval bases—presents a serious counterintelligence challenge. The blurred line between civilian and military roles under China’s civil-military fusion strategy means that even its ostensibly commercial vessels may be tasked to collect information or enable other PRC military objectives. We should keep this in mind when considering whether to continue to allow essentially-unfettered access by them to our ports.
Note: this piece was written with the assistance of artificial intelligence