China's most advanced aircraft carrier, the Fujian, recently sailed through the Taiwan Strait and into the South China Sea - both highly sensitive waterways - as part of its sea trials and possibly ahead of its formal entry into service.
The Chinese Navy said in a statement on Friday that the journey was conducted to carry out scientific research and training missions. First unveiled in 2022, the Fujian is the country's third aircraft carrier and began sea trials last year. It has yet to formally enter service.
"This cross-regional trial and training exercise for the Fujian is a routine arrangement in the carrier's construction process and is not directed at any specific target," it added.
The sailing comes as US Marines and Japanese counterparts stage a fortnight of exercises on the nearby island of Okinawa with the Typhon missile system and other advanced anti-ship weapons. The drills are due to run until September 25.
Japan's defence ministry said late on Thursday that the Fujian had entered the East China Sea, sailing southwest toward Taiwan, accompanied by two Chinese missile destroyers.
Taiwan's defence ministry said it has been monitoring the situation with joint intelligence surveillance and has taken appropriate measures.
A senior Taiwan security official told Reuters the Fujian, named after the Chinese province which faces the island, was likely heading to the South China Sea in preparation for its commissioning ceremony.
While China's defence ministry did not respond to a request for comment, Chinese naval expert Li Jian told a social media account affiliated with state propaganda broadcaster CCTV the sailing may be the final phase of trials before the Fujian enters service.
China has, over the past five years or so, stepped up its military presence around Taiwan, including staging war games, to assert its sovereignty claims.
The Fujian, designed and built domestically, is larger and more advanced than the Shandong, commissioned in late 2019, and the Liaoning, which China bought second-hand from Ukraine in 1998.
With a flat deck and electro-magnetic catapults to launch aircraft, the Fujian is expected to host a larger and wider range of planes than the other two carriers - including early-warning aircraft and, eventually, China's first carrier-capable stealth jet fighters.
Chieh Chung, a researcher at the Taipei-based Association of Strategic Foresight, said that once the Fujian enters service it would enable China to maintain three carrier strike groups in tactical positions across the Western Pacific.
Given the Fujian can also carry fixed-wing early warning aircraft, unlike the two other carriers, that extends its long-range "defence zone" beyond 600 kilometres (373 miles), he added.
Regional security analysts and military attaches are watching the Fujian's trials closely, in part to see how effectively China's navy can co-ordinate full-blown carrier operations with escort ships and submarines.
(Reporting by Beijing newsroom; Additional reporting by Ben Blanchard and Yimou Lee in Taipei, Greg Torode in Hong Kong and Kantaro Komiya in Tokyo; Editing by Himani Sarkar and Edwina Gibbs)