Tensions spiked on May 3, when a Chinese coastguard vessel launched a helicopter after a Japanese civilian aircraft had approached the area. According to Iwata, Beijing sought to portray the move as “an exercise in proclaiming its sovereignty” in response to a Japanese intrusion.

“By portraying the move as reactive, they are attempting to establish a precedent for their territorial claim,” he said.

Two Chinese coastguard vessels entered the area again on June 14, marking the 16th day armed Chinese ships had been tracked inside Japanese waters this year.

According to Iwata, Beijing’s coastguard is “already preparing” for a potential operation to seize the islands.

“They have been steadily upgrading their equipment and capabilities, including ship deployments, helicopter operations and specialised training for personnel tasked with disembarking and carrying out missions on the ground,” he said.

Iwata also noted recent legal changes that might lay the groundwork for a future confrontation. “On the legal front, [Chinese President] Xi Jinping amended regulations in 2024 that authorise the detention of foreign vessels and individuals that enter what China claims as its territorial waters,” he said, adding that Beijing’s coastguard drills increasingly resembled full-scale naval exercises.

Many observers share the belief that China wants to control the islands and that, sooner or later, it will try to wrest control and sovereignty away from Japan.

“I think there is a broad consensus on that,” said Ryo Hinata-Yamaguchi, associate professor at Tokyo International University’s Institute for International Strategy.

“The increase in the Chinese pressure and presence has not really been hidden and these ‘grey-zone’ efforts have been going on for some years, in the same way that China has been exerting pressure elsewhere,” he told This Week in Asia.

However, he argued that an occupation of the islands would have limited strategic value for Beijing on its own.

“What would China gain by just occupying the Senkakus?” he asked. “I do not see that as an end in itself, although it could be part of a larger goal that would include occupying other islands.”

Beijing sees Taiwan as part of China to be reunited by force if necessary. Most countries, including the US, do not recognise Taiwan as an independent state, but Washington is opposed to any attempt to take the self-governed island by force and is committed to supplying it with weapons.

Hinata-Yamaguchi said China’s military still appeared unprepared for such a major operation, as it continued to expand and modernise its air, sea and ground forces.

Should China attempt to seize the Senkakus, he said Japan would respond in concert with Washington under the US-Japan security treaty.

Others, however, voiced greater uncertainty.

“I would not say that an attack on the islands is likely now, but we can see how an argument could be made why China would try to take them,” said Robert Dujarric, co-director of the Institute of Contemporary Asian Studies at Temple University’s Tokyo campus.

Diaoyu-Senkaku islands spat deepens as Japan warns China over coastguard ships in East China Sea

Dujarric cited the geopolitical turmoil elsewhere in the Middle East and Ukraine, as well as the “weak government in Japan” and the extent to which Japanese people would be willing to defend the islands.

Suggestions that Japan should deploy armed forces on the islands would inevitably trigger fierce backlash from Beijing and could serve as a “tripwire” for a military reaction, he added.

The growing unease is reflected in local opinion, particularly in Okinawa prefecture, where the Yaeyama Daily News has published reader comments expressing alarm.

“It is only a matter of time before Chinese people – probably military personnel disguised as fishermen – land on the Senkaku Islands,” read one comment. “If that happens, the islands will effectively be under the control of China.”

Another read, “It has become the norm for Chinese ships to violate our territorial waters. China’s approach is to do more, little by little, and they will eventually take control. They will take everything.”

A third commenter demanded a stronger government response to assert Japan’s sovereignty: “How long is the Japanese government going to leave this matter unattended? They have not taken adequate countermeasures. They should not be afraid to build structures on the islands and reaffirm Japanese control.”

Analysts warned that the Chinese fighter’s manoeuvres and other similar actions should not be taken lightly.

“We should see these sorts of actions as threats,” Toshimitsu Shigemura, a professor of politics and international relations at Tokyo’s Waseda University, told This Week in Asia.

“If either of those aircraft had made even a small mistake, then there could very easily have been contact and potentially even a crash. At the moment this is at the diplomatic level, but an error could very quickly see it escalate into something far more serious.”

There is a precedent, according to Shigemura, who points to an April 2001 incident off the Chinese island of Hainan, when a US Navy EP-3 signals intelligence aircraft collided with a Chinese J-8 interceptor. The Chinese pilot was killed when his aircraft crashed into the sea between Hainan and the Paracel Islands in the South China Sea.

The US aircraft was forced to make an emergency landing on Hainan and its 24 crew members were detained and questioned by Chinese authorities for 10 days until Washington issued a sufficiently ambiguous statement that the crisis could be defused without either side losing face.

The US has since complained that its reconnaissance aircraft have been “harassed” in international airspace over the Pacific by Chinese military planes, with The Washington Post in 2023 detailing 180 “risky intercepts” in the previous two years.

The incidents included Chinese fighters approaching to within three metres of American aircraft, discharging chaff and, in one case, a pilot “even flipped a middle finger in a brazen show of intimidation”, the newspaper quoted defence officials as saying.

Shigemura believes there are a number of reasons behind the aggressive manoeuvres against the Japanese aircraft and the broader deployment of two aircraft carrier groups beyond the “first island chain” and into the Pacific.

“The Japanese islands are a big obstacle for the Chinese military, and it is relatively easy to monitor the movement of ships and aircraft that want to get into the Pacific and have freedom of activity,” he said. “The Chinese have done very little training beyond their own coastal waters, so this is also an important opportunity for that.”

The Chinese units would also inevitably be watching for the response of Japanese and US forces to their exercises and movements, including whether they would be acting in concert or independently, Shigemura suggested.

“I think it is pretty clear that we should also see this as a political message to Tokyo to not cooperate with the Trump administration as it puts more and more pressure on China,” he said. “The message is that greater cooperation with Washington will mean China stepping up its presence and activities in the Pacific just off Japan’s southern coast.”

Online reactions in Japan have been almost entirely angry.

“Simply put, this is tailgating in the air and at sea and is an extremely provocative and dangerous act,” said a message linked to a Tokyo Broadcasting System report.

“Even if this is merely a threat from China, we must be careful because ‘grey-zone situations’ around our country are expanding and diversifying and the possibility of accidental collisions occurring due to misperceptions, misjudgments or miscommunication is increasing.”