Chinese fighter jets directed their fire-control radar at Japanese aircraft over international waters on Saturday near Japan's Okinawan islands in two separate incidents that Japan's defense minister condemned as "dangerous".

"These radar illuminations went beyond what is necessary for the safe flight of aircraft," Japan's Defense Minister Shinjiro Koizumi said in a post on X. Japan, he said, had lodged a protest with China over the "regrettable" incident.

The encounters over the islands, which are close to disputed territory claimed by both Japan and China, will likely ratchet up tension between the neighbours. Relations have already soured after Prime Minister Sanae Takaichi warned that Japan could respond to any Chinese military action against Taiwan if it also threatened Japan's security.

The Chinese J-15 jets were launched from China's Liaoning aircraft carrier, which was maneuvering south of the Okinawan islands along with three missile destroyers, Japan said.

Democratically governed Taiwan is claimed by Beijing and lies just 110 kilometres (68.4 miles) from Japan's westernmost Yonaguni Island.

This photo taken on June 11, 2025 shows Takamatsu Gushiken, a volunteer who recovers the remains of war dead to be reunited with their families, riding his motorcycle to the city of Itoman from Ginowan city, Okinawa Prefecture.
This photo taken on June 11, 2025 shows Takamatsu Gushiken, a volunteer who recovers the remains of war dead to be reunited with their families, riding his motorcycle to the city of Itoman from Ginowan city, Okinawa Prefecture. (credit: PHILIP FONG/AFP via Getty Images)

Tensions between China and Japan rise up

Calls to China’s defence ministry outside of office hours on Sunday were not answered.

Japan hosts the biggest overseas concentration of US military power, including warships, aircraft and troops, with a big chunk of that contingent, including thousands of US Marines based in Okinawa.

The US State Department was not immediately available for comment.

The Chinese J-15 jets involved in the two incidents on Saturday were launched from China's Liaoning aircraft carrier, which was maneuvering south of the Okinawan islands along with three missile destroyers, Japan said.

On Thursday, China was deploying a large number of naval and coast guard ships across East Asian waters, which at one point numbered more than 100, Reuters reported, citing sources and intelligence reports.

Taiwan's government described that build-up as posing a threat to the Indo-Pacific region. Japan said it was monitoring Chinese activity closely.