On Thursday, Japan’s Self-Defense Forces observed China’s largest and most advanced aircraft carrier, the Fujian, in the East China Sea, marking its first sighting by Japan.

The carrier was located approximately 200 kilometers northwest of the disputed Senkaku Islands (known as Diaoyu in China). A Japanese P-3C aircraft identified three vessels and collected information, as reported by the Joint Staff Office.

Meanwhile, China confirmed on Friday that its third and newest aircraft carrier, the Fujian, recently sailed through the sensitive Taiwan Strait to carry out “scientific research trials and training missions” in the South China Sea.

China has invested billions of dollars into modernising its military in recent years, a trend that has unnerved some governments in East Asia despite China insisting its aims are peaceful.

China has two carriers in operation — the Liaoning and Shandong — with the Fujian currently undergoing sea trials.

China’s navy said on Friday that undertaking cross-regional trials “is a normal part of the aircraft carrier’s construction process”.

It is “not directed at any specific target”, a spokesman for the Chinese navy, Leng Guowei, said in a statement.

However, its transit through the sensitive Taiwan Strait was intended to signal “China’s rise as a strong military power, and beyond that, a maritime great power”, said Collin Koh, a senior fellow at the S. Rajaratnam School of International Studies in Singapore.

“It’s to flex China’s newfound military strength and send a veritable signal to potential adversaries,” he said.

Taiwan’s Ministry of National Defence said Friday it had used “joint intelligence, surveillance and reconnaissance means to fully grasp the situation and responded accordingly”.

Japan’s defence ministry identified three Chinese naval ships advancing southwest in waters approximately 200 kilometres northwest of one of the disputed Senkaku Islands. “Among these, the Fujian aircraft carrier was confirmed by the Japan Maritime Self-Defense Force for the first time,” it said in a statement.

Japan said in July that China’s intensifying military activities could “seriously impact” its security, citing the first confirmed incursion by a Chinese military aircraft into its airspace last August in an annual threat assessment.

China said that a coastguard fleet had “patrolled within the territorial waters of the Diaoyu Islands” on Friday.

Last year, Chinese vessels sailed near the Japanese-administered islands a record 355 times, according to Tokyo.

Compared to the other seas, the South China Sea “presents a more challenging environment with harsher conditions, making the trials more rigorous” for the Fujian, said Song Zhongping, a Chinese military commentator.

After undergoing sea trials and completing further adaptive training, the Fujian will likely be commissioned into active service, Song told AFP.

The Soviet-built Liaoning is China’s oldest aircraft carrier, commissioned in 2012, while the Shandong entered service in 2019.

Analysts at Washington-based think tank CSIS have said that Fujian is expected to feature more advanced take-off systems, allowing the Chinese air force to deploy jets carrying larger payloads and more fuel.

China has stepped up a massive expansion of its naval forces in recent years as it seeks to grow its reach in the Pacific and challenge a US-led alliance.

The US Department of Defense said in a December report that China numerically has the largest navy in the world, with a battle force of more than 370 ships and submarines.

Beijing said in June that its Liaoning and Shandong carrier formations conducted combat drills in the western Pacific Ocean, unsettling regional neighbours including Japan.

A Taiwanese security official also said that in May, Beijing had deployed its two aircraft carrier groups around the island. The Chinese Communist Party has refused to rule out using force to seize control of Taiwan, a democratic, self-ruled island that China insists is part of its territory.