The most valuable spy near a naval exercise may not be a submarine or a satellite. It may be the container ship steaming quietly past on the horizon, stacked with boxes and bristling with antennas that look exactly like every other merchant vessel afloat.

That is the allegation at the centre of a Reuters report published on September 1: that COSCO, China's state-run shipping giant and one of the largest carriers on Earth, has spent decades quietly gathering signals intelligence from its cargo fleet — scooping up communications from ships and aircraft along the coastlines of North America, Europe and Asia.

For an aviation audience it is a pointed detail. Signals intelligence does not stop at the waterline: the same passive receivers that log a warship's radar can catalogue military radio traffic and datalinks overhead, feeding the electronic order of battle that any modern air force depends on.

Hidden in plain sight

The officials, speaking anonymously, described a "decades-long intelligence-collection partnership" between COSCO and Beijing. They would not specify the hardware, but insisted it was "sophisticated signals intelligence collection" equipment rather than the ordinary radios and radars any ship carries. On a modern container vessel already festooned with antennas, hiding another one is trivially easy.

The legal machinery makes the arrangement plausible. China's 2017 National Intelligence Law obliges every organisation and citizen to support state intelligence work when asked — and to be protected for doing so. A commercial fleet that dwarfs any rival on the planet becomes, on paper, a standing intelligence network that costs Beijing almost nothing to run.

Reuters video: China's "gray-zone" pressure at sea, the backdrop against which the COSCO allegations land.

The idea is not new. A report published in April 2025 by the U.S. Naval War College's China Maritime Studies Institute laid out how Beijing already threads intelligence specialists — "information personnel" — through its ostensibly civilian fishing and shipping fleets.

Denials and precedent

Beijing rejected the report flatly. China's embassy in Washington called it baseless, with spokesperson Liu Chang telling Reuters that the government would never ask a company to break local laws to gather intelligence abroad.

Skeptics note the tactic is hardly unique to China. Cold War navies stuffed "trawlers" with receivers; Russia's sanctions-dodging shadow tanker fleet has reportedly moonlighted as a sensor network; and Western powers, the United States included, have long used nominally civilian ships and aircraft for the same ends. What unsettles US officials is scale. With Chinese merchant hulls in nearly every major port, the opportunities to listen are almost limitless — and almost impossible to police.

No hard evidence has been produced publicly, and the claims remain officials' assessments rather than proof. But the logic is hard to argue with: if the ships are already sailing past the exercises, the bases and the flight corridors, the cost of switching on a receiver is close to zero.

Sources: Reuters (Sep 1, 2026); TWZ (Joseph Trevithick); U.S. Naval War College China Maritime Studies Institute (April 2025).