The United States has for the first time criticised China for aiming radars at Japanese military aircraft during a training exercise last week, incidents that the Asian neighbours have given differing accounts of amid escalating tensions.

The run-in near Japan’s Okinawa islands comes after Japanese Prime Minister Sanae Takaichi triggered a dispute with Beijing last month with her remarks on how Tokyo might react to a hypothetical Chinese attack on Taiwan.

China claims democratically governed Taiwan and has not ruled out using force to take control of the island, which sits just over 100 km (62 miles) from Japanese territory and is surrounded by sea lanes that Tokyo relies on.

“China’s actions are not conducive to regional peace and stability,” a State Department spokesperson said late on Tuesday (December 9, 2025), referring to the radar incident.

“The U.S.-Japan Alliance is stronger and more united than ever. Our commitment to our ally Japan is unwavering, and we are in close contact on this and other issues.”

China’s foreign ministry did not immediately respond to a request for comment.

Japan, late on Tuesday (December 9), scrambled jets to monitor Russian and Chinese air forces conducting joint patrols around the country.

Most serious incident in years

The Chinese fighter jets aiming their radars at the Japanese planes on Saturday (December 6) was the most serious run-in between the East Asian militaries in years.

Such moves are seen as a threatening step because it signals a potential attack and may force the targeted plane to take evasive action. Tokyo blasted the moves as “dangerous”.

Beijing, however, said that the Japanese aircraft had repeatedly approached and disrupted the Chinese navy as it was conducting previously announced carrier-based flight training east of the Miyako Strait.

Speaking to reporters in Taipei on Wednesday (December 10), Taiwan President Lai Ching-te said China’s drills were “very inappropriate behaviour”.

“We also call upon China to demonstrate the responsibility befitting a major power. Peace is priceless; war has no winners. Peace must be fostered by all parties, and China shares this responsibility,” he said.

Relations between Asia’s two largest economies have soured sharply since Takaichi told parliament last month that a Chinese attack on Taiwan could amount to a “survival-threatening situation” and trigger a potential military response from Tokyo.

Beijing has demanded she retract the remarks, accused Tokyo of threatening it militarily and advised its citizens not to travel to Japan.

U.S. Ambassador to Japan George Glass has publicly expressed support for Japan in several social media posts since the diplomatic dispute began, but President Donald Trump and other senior U.S. officials have remained silent.

Mr. Trump, who plans to visit Beijing next year for trade talks, telephoned Takaichi last month, urging her not to escalate the dispute, people with knowledge of the matter told Reuters.

Japan and Australia urged calm on Sunday (December 7, 2025) after Chinese military aircraft locked radar on Japanese fighter jets, a month after the Japanese leader’s recent remarks on Taiwan that stirred tensions between Tokyo and Beijing.

Defence Minister Shinjiro Koizumi said Japan formally protested the incident, calling it “an extremely regrettable” act and “a dangerous” one that “exceeded the scope necessary for safe aircraft operations.”

“We have lodged a strong protest with the Chinese side and demanded strict preventive measures,” Mr. Koizumi said.

Japan’s Defence Ministry said China’s military aircraft J-15 took off from the Chinese carrier Liaoning near the southern island of Okinawa on Saturday (December 6) and “intermittently” latched its radar on Japanese F-15 fighter jets on two occasions, for about three minutes in the late afternoon and for about 30 minutes in the evening.

It was not made clear whether the radar lock incident involved the same Chinese J-15 both times.

Japanese fighter jets had been scrambled to pursue Chinese jets that were conducting aircraft takeoff and landing exercises in the Pacific.

They were pursuing the Chinese aircraft at a safe distance and did not take actions that could be interpreted as provocation, Kyodo News agency said, quoting defence officials, when the radar lock happened. There was no breach of Japanese airspace, and no injury or damage was reported from the incident.

Senior Colonel Wang Xuemeng, spokesperson for the Chinese Navy, defended China’s flight training near the Miyako island on Saturday (December 6), saying Beijing announced the exercises beforehand and accused Japanese aircraft of “harassment”. Mr. Wang, in a statement posted Sunday (December 7) on the Chinese Ministry of Defence website said, “We solemnly asked the Japanese side to immediately stop slandering and smearing, and strictly restrain its frontline actions. The Chinese Navy will take necessary measures in accordance with the law to resolutely safeguard its own security and legitimate rights and interests.”

Relations between Japan and China have worsened after Japan’s Prime Minister Sanae Takaichi said in early November its military could get involved if China were to take action against Taiwan, the self-governing island that Beijing claims as its own.

Japan and Australia, whose Defence Ministers held their scheduled talks in Tokyo on Sunday (December 7), expressed worry over the development.

“We are deeply concerned by the actions of China in the last 24 hours,” Australian Defence Minister Richard Marles told a joint news conference on Sunday (December 7) after holding talks with Mr. Koizumi. “We expect those interactions to be safe and professional.”

Australia does “not want to see any change to the status quo across the Taiwan Straits”, Mr. Marles said, adding that China is his country’s largest trade partner and he wants to have productive relations with Beijing.

“We continue to advocate to China about these issues again, in a very calm, sensible and moderate way,” he said.

Talks deepen between Japan and Australia amid rising China tensions

Japan and Australia, during Sunday talks, agreed to bolster military ties to lead the region’s multilateral defence cooperation. The two Ministers agreed to form a comprehensive “framework for strategic defence coordination” and discuss further details.

Tokyo has been accelerating its military buildup while expanding its defence ties beyond its only treaty ally, the United States. It now considers Australia to be a semi-ally.

Mr. Marles also visited a Mitsubishi Heavy Industries shipyard in Nagasaki on Saturday (December 6) to observe production of the upgraded Mogami-class frigate that his country chose in September as a replacement for its aging fleet.

Saturday’s (December 6) radar lock is believed to be the first involving Japanese and Chinese military aircraft. In 2013, a Chinese warship targeted a radar on a Japanese destroyer, Kyodo mentioned.

Fighter jets use radars for search operations or fire control ahead of a missile launch.

Elsewhere in the Pacific, the Philippine coast guard said China fired three flares toward a fisheries bureau plane on patrol in the South China Sea on Saturday (December 6). Chinese forces fire flares to warn planes to move away from what they consider their airspace over the disputed waters.

Japanese Prime Minister Sanae Takaichi said on Friday (November 21, 2025) that she wants “constructive” ties with China and that the country’s stance on Taiwan remains “unchanged” amid a spat with Beijing over the island.

“At the end of last month, President Xi [Jinping] and I confirmed the broad direction of comprehensively advancing our strategic, mutually beneficial relationship and building a constructive and stable relationship,” Ms. Takaichi told reporters.

“The government’s position remains unchanged” on Taiwan, she added.