(Beijing) Beijing said on Wednesday that the former Chinese naval officer who illegally entered Taiwan on Sunday aboard a speed boat had acted “on his own accord” and would be “punished” if necessary upon his return to mainland China .

The island announced Tuesday a strengthening of its security measures following the incident, citing an attack on “national security” possibly orchestrated by Beijing.

The Taiwan Affairs Office (TAO) in Beijing, however, assured Wednesday that the man had acted “on his own initiative” and that the Taipei authorities had “no reason to be so alarmed”.

“We will punish him in accordance with the law when he returns to mainland France,” said his spokesperson, Chen Binhua.

Taiwan’s coast guard arrested the man on Sunday after his boat collided with other vessels on the Tamsui River, which connects the capital Taipei to the island’s northern coast.

The 60-year-old told the coast guard he wanted to “defect,” according to the semi-official Central News Agency.  

According to Taiwanese Minister of Maritime Affairs Kuan Bi-ling, the man is a former captain in the Chinese navy and an investigation has been opened into his motivations.

Taiwan is constantly on guard for potential Chinese spies or maneuvers intended to test its defenses.

On Wednesday, the head of Taiwan’s National Security Bureau, Tsai Ming-yen, told Parliament that the incident could fall under a so-called “gray zone” operation, a term designating hostile action not going as far as an act of war.

The Taiwan Coast Guard said 10 of its personnel were punished for failing to intercept the boat.