The Japanese government declined to comment on the ship, citing operational caution.
But China confirmed on Thursday that its military had responded to “the activities of Japanese Self-Defense Forces warships that entered the Taiwan Strait.”
“China is very wary of the political intentions behind Japan’s actions and has lodged strong representations with Japan,” Foreign Ministry spokesperson Lin Jian said.
Chinese state-run newspaper Global Times cited anonymous sources as saying the Chinese military had “conducted tracking and surveillance along the entire route (of the ship) and was controlling the situation.”
The United States and its allies have stepped up patrols to assert freedom of navigation in the 180-kilometer (112-mile) Taiwan Strait.
Both the U.S. and Taiwan say the route is a major shipping and trade route for about half of the world’s container fleet and is open to all naval vessels as it is part of international waters.
Beijing, which claims sovereignty and jurisdiction over the strait, objects.
For decades, the U.S. Pacific Fleet was the only foreign navy to regularly transit the strait. But Canada, Australia, Britain, and France have recently joined in. Two weeks ago, Germany sent two naval vessels through the strait for the first time in decades.
The Chinese military has accused Germany of increasing security risks by sailing through the strait on September 13, but Berlin said it acted in accordance with international standards. It was the first time in 22 years that a German naval vessel had sailed through the strait.
The move is highly political in nature and designed to show China that the United States and its allies do not accept Beijing’s demands.
For Japan, this is another major step away from its longstanding policy of not directly challenging China.
On Thursday, a Japanese cabinet minister did not confirm details of the naval operation, but said Japan felt a strong sense of crisis after Chinese forces repeatedly violated its airspace in a short period of time.
Taiwan has not commented on the route, but on Wednesday its Defense Ministry said it had detected a surge in the number of Chinese military aircraft operating around the island.
Beck Strating, professor of international relations at Australia’s La Trobe University, said Japan’s reported transit was “part of a broader pattern of expanding naval capabilities by countries in Asia and beyond concerned about China’s maritime claims”.
“Japan in particular has been fighting against China’s ‘gray zone’ tactics in the East China Sea,” she told AFP.
Analysts say gray zone warfare tactics aim to weaken an enemy over the long term.
Last week, Beijing sent an aircraft carrier between two Japanese islands near Taiwan for the first time. In August, a Chinese spy plane flew over Japanese airspace, prompting Tokyo to condemn the incursion as a “serious violation of sovereignty” that was “totally unacceptable.”
Leaders of the Quad Group of nations – Japan, Australia, India and the United States – said last week they would expand cooperation on maritime security to counter China’s growing assertiveness in the South China Sea.
