China protests first transit of Taiwan Strait by Japanese warship

China lodged a protest with Japan on Thursday after Tokyo for the first time sailed a warship through the Taiwan Strait, along with vessels from Australia and New Zealand.

Beijing has China "lodged stern representation with the Japanese side," Foreign Ministry spokesman Lin Jian told reporters in Beijing.

The warships transited the waters that divide Taiwan from mainland China on Wednesday, prompting Beijing's People's Liberation Army to launch "tracking and monitoring" operations.

Japan's Maritime Self-Defense Force vessel, the Sazanami, along with the ships from Australia and New Zealand, headed southward from the East China Sea through the narrow waterway.

The warships are believed to hold drills in South China Sea.

"The Taiwan question concerns China's sovereignty and territorial integrity, and concerns the political foundation of China-Japan relations," said Lin.

"It is a red line that must not be crossed."

Japan, Australia and New Zealand sailing their warships comes weeks after Germany recently sailed its warship through the Taiwan Strait for the first time in 22 years.

This is also the first time since 2017 that New Zealand sailed one of its warships through the Taiwan Strait.

The US and its allies have regularly sailed their warships and flew military planes through the region, drawing criticism from China, which considers such moves violations of its sovereignty over waters and airspace that span across Taiwan Strait.

China considers Taiwan its "breakaway province," while Taipei has insisted on its independence since 1949.

Lin said China "always deals with foreign warships' Taiwan Straits transits in accordance with law and regulations, and maintains high alert on any potential moves that could harm China's sovereignty and security."

Meanwhile, Taiwan's Defense Ministry said it detected 43 Chinese military aircraft and eight naval vessels operating around the island nation early Thursday.