- Japan is investigating one of its naval destroyers after it sailed into Chinese waters near Taiwan.
- Japanese media reported that the incident occurred on July 4 as China conducted live-fire drills.
- Authorities say it might have been a mistake, but are still questioning the warship's captain.
Japan's defense ministry is investigating officers of a naval destroyer that entered Chinese territorial waters for about 20 minutes on July 4, according to local reports.
Kyodo News reported on Thursday that the Maritime Self-Defense Force destroyer Suzutsuki was monitoring Chinese live-fire drills on the coast of China's Zhejiang province when it pushed into Chinese territory.
Zhejiang's maritime authority issued a notice on July 3 saying it would conduct live-fire drills from 6 a.m. on July 4 to 10 p.m. the next day, designating a no-sail zone on the coast.
Per Kyodo News, the Suzutsuki approached the no-sail zone on July 4 and was told by Chinese vessels to turn back, but accelerated and continued deeper into Chinese territory.
The vessel was about 12 nautical miles from Zhejiang's coast, the outlet reported, citing two anonymous officials.
Zhejiang is one of mainland China's closest provinces to Taiwan.
The Suzutsuki departed Chinese waters about 20 minutes later, and Kyodo News sources said they suspected the accident may have been caused by a "procedural error."
However, Japanese authorities have yet to publicly explain exactly what caused the maritime incident. Kyodo News reported that the captain of the Suzutsuki is being questioned by Japan's defense ministry.
International law allows ships from one state to pass through another's territory as long as the vessel does not threaten the latter's security.
"At the very least, there is no legal problem," a Japanese government official told local outlet Sankei Shimbun.
However, Kyodo News cited Chinese diplomatic officials saying that Beijing believes the Suzutsuki broke Chinese laws by failing to request entry.
According to Reuters, Chinese Foreign Ministry spokesperson Lin Jian said on Thursday that his office had lodged a complaint with Japan's government over the Suzutsuki's "illegal and improper actions."
The Suzutsuki is an Akizuki-class destroyer, which is about 500 feet long and can take a crew of about 200.
Sankei Shimbun reported that the destroyer was scheduled for several public viewings in Akita, Hachinohe, and Aomori throughout July, but these showings have since been canceled.
The risk of war between both nations because of this maritime incident is low, despite coming as Sino-Japanese relations remain tense, Ian Ja Chong, an assistant professor of political science at the National University of Singapore, told Business Insider.
"But it doesn't seem that the PRC is really playing things up that much," said Chong, referring to China's full official name.
Japan's investigation into the ship's captain may soothe China's indignance, he added.
"It gives Beijing an off-ramp. The issue is whether they want to take it," he said.
Tokyo has also often noted China's incursions into its own waters, Chong said.
China has repeatedly sent armed coast guard vessels to patrol waters around the Senkaku islands, which are under Japanese control. Beijing claims the islands are China's, and calls them the Diaoyu islands.
Chinese naval ships have also entered Japanese waters before, including in February 2023, when a survey vessel encroached into Japan's territorial waters near Kagoshima prefecture.
Press centers for the Japanese government and China's foreign ministry did not immediately respond to requests for comment sent by Business Insider.
July 12, 2023: This story was updated to reflect commentary from Ian Ja Chong, a professor at the National University of Singapore/