A Chinese man arrested after his speedboat illegally entered a Taipei harbour is a former PLAN captain who may have been investigating the island’s defences, senior Taiwanese officials said on Tuesday.

Taiwan’s coast guard arrested the man on Sunday in Tamsui, a coastal neighbourhood, after his boat entered a river leading into Taipei. This incident occurs amid ongoing tensions between Taiwan and China. China considers Taiwan as its territory, a claim firmly rejected by Taipei.

Kuan Bi-ling, head of Taiwan’s Ocean Affairs Council, which oversees the coast guard, told reporters that the man was “quite refined and well-presented” and had previously served as a Chinese navy captain.

18 earlier cases

Kuan mentioned that over the past year, there have been 18 similar cases, mostly involving Taiwan-controlled islands near the Chinese coast. “Looking at the accumulated cases in the past, we can’t rule out that this is a test,” she said, suggesting a possible probe of Taiwan’s ability to detect such vessels.

China’s Taiwan Affairs Office and its defence ministry did not immediately respond to requests for comment.

Grey Zone Tactics

Taiwan Defence Minister Wellington Koo said the boat incident could be another example of China’s “grey zone” tactics against the island. Grey zone warfare involves irregular tactics designed to exhaust a foe without open combat, such as floating surveillance balloons over the island.

“These grey zone tactics have always existed,” Koo said. “We must always maintain our vigilance and cannot rule out the possibility of taking countermeasures.”

In March, two Taiwanese fishermen strayed into Chinese waters near the Taiwan-controlled Kinmen islands, close to China’s coast. One, a Taiwanese military officer, remains detained in China, while the other was released shortly after.

With Inputs from Reuters