Beijing claims it's found 'underwater lighthouses' that its foes use for espionage

China has accused unnamed foreign entities of using devices hidden in the seabed and bobbing on the waves to learn its maritime secrets.

The nation’s Ministry of State Security made the allegation in a Tuesday post to its WeChat account claiming authorities seized a variety of devices from the sea floor.

The ministry alleged some of the devices acted as "secret sentinels" that operated for lengthy but unspecified periods for the purpose of "covertly collecting marine hydrological information and data on the activities of various ships around them and serving the preset of the battlefield environment."

The ministry further alleged it found drifting devices.

Those "secret agents" are "detecting and grasping the real-time situation in the sea area; Some of them act as underwater 'lighthouses' to show the direction of submarines of other countries that have intruded into China's waters, in a vain attempt to conceal their whereabouts, thus seriously threatening China's national security," the agency continued.

The ministry resolved to prevent security risks and defend China's sovereignty, security, and development interest in the maritime sphere.

• Three Chinese balloons float near Taiwanese airbase
• Drone maker DJI sues Pentagon over 'Chinese military company' label
• China again claims Volt Typhoon cyber-attack crew was invented by the US to discredit it
• China claims Taiwan, not civilians, behind web vandalism

The ministry has made similar allegations before. In May of this year, it also claimed "various types of 'maritime espionage' have been discovered in China's waters" for the purpose of endangering China's national security.

At that time, it posted a photo of a device that it claimed was snapped by a fisherman.

The ministry described the device as "specially developed and manufactured" and functioning either automatically or remotely.

"These devices have a variety of functions, not only to realize the dynamic perception of sensitive data, detection and collection, but also to store data, analysis, transmission and other functions," wrote the ministry at the time on its WeChat channel. "Most devices also have a self-destruct function, which can be automatically destroyed after the completion of the mission according to a pre-set program."

China asserts sovereignty over nearly the entire South China Sea and is at odds with neighboring countries like Brunei, Malaysia, the Philippines and Vietnam over territorial rights.

The Middle Kingdom is often accused of sending mechanisms capable of spying to foreign nations – as demonstrated last February when a balloon was shot down over the United States.

Balloons, aircraft and ships are often commonly found in or near Taiwan – an island China has long declared will eventually re-unify with the mainland.

China is currently growing its navy very fast, according to think tank Center for Strategic and International Studies.

"If China continues to expand its fleet at the current pace and the United States does not revitalize its shipbuilding industry, China will grow increasingly likely to emerge victorious from interstate war, especially a prolonged great power war," wrote CSIS this June.

"The result is a China that will grow more confident projecting power, threatening its less powerful neighbors, and disregarding US efforts to deter such behavior," it added.

That prediction of threats is already apparent: China regularly carries out military drills by land, air, and sea near Taiwan. One round of exercises took place just three days after the May inauguration of Taiwan's new president William Lai Ching-te, an avowed opponent of reunification with China. Two weeks ago China reportedly sent 34 naval vessels and 125 aircraft around the island.

Beijing is well aware that any kinetic action in Taiwan would be enormously disruptive to the global economy. It would likely impact key chipmakers like TSMC that help to give Western powers an edge in many areas of information technology.

Allegations of salty spy boxes are therefore more than the submarine equivalent of saber-rattling. ®