China's most advanced aircraft carrier, the Fujian, recently sailed through the Taiwan Strait and into the South China Sea - both very sensitive waterways - as part of its sea trials.
The Chinese navy said in a statement on Friday that the journey was made to conduct scientific research trials and training missions. First unveiled in 2022, the country's third aircraft carrier began sea trials last year and 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 exercises are due to run until September 25.
Japan's defense 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 defense ministry said it has been monitoring the situation with joint intelligence surveillance and has taken appropriate measures.
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.
Taiwan's government rejects Beijing's sovereignty, saying only the island's people can decide their future.
China considers the Taiwan Strait to be its territorial waters. Taiwan, the United States and many of its allies say it is an international waterway.
The South China Sea has been another site of increased Chinese military activity. China claims most of the sea - claims that are contested by many countries including the Philippines and Vietnam.
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.
Regional security analysts and military attaches are watching the Fujian's trials closely, in part to see how effectively China's navy can coordinate full-blown carrier operations with escort ships and submarines.
