WASHINGTON

Japanese Defense Minister Shinjiro Koizumi has raised the issue of Tokyo's air engagement with China during a phone call with US Defense Secretary Pete Hegseth about regional security, according to a statement by Japan.

Hegseth and Koizumi on Thursday discussed China's military activities and the importance of realistic training and exercises across Japan, including in the Southwest Islands, as well as Japan's efforts to increase its defense spending and strengthen its capabilities, the Pentagon said in a statement.

They "reaffirmed the importance of the U.S.-Japan Alliance and underscored their commitment to deterring aggression in the Asia-Pacific," the statement added.

Koizumi and Hegseth discussed "candid views on increasingly severe security situation in the Indo-Pacific region," including the radar incident, said a statement from the Japanese Defense Ministry on US social media company X.

Tokyo claimed on Saturday that Chinese J-15 aircraft from the carrier Liaoning locked radar on two Japanese F-15 jets over high seas, southeast of Okinawa’s main island.

China, however, said in a news conference that the maneuvers were “professional, secure, restrained and beyond dispute,” adding that it is “common practice” for carrier-borne aircraft to switch radar on during training.

Hegseth and Koizumi expressed "serious concern over any actions to increase regional tensions, as China’s actions are not conducive to regional peace and stability, and concurred to closely communicate and collaborate with each other," the Japanese statement said.

They also reaffirmed to continue "further strengthening the Alliance capabilities to deter and respond, with a sense of urgency and speed," it added.

Beijing, in reaction to the Hegseth-Koizumi phone call, expressed hope that "the international community will tell right from wrong and not be deceived by the Japanese side. Japan’s allies, in particular, need to see clearly the Japanese side's intentions and avoid being misled by it," Chinese Foreign Ministry spokesperson Guo Jiakun said during a regular news conference in Beijing.

Separately, China on Friday said that several small aircraft of the Philippines were “tracked, monitored, warned, and resolutely expelled,” after they entered “into the airspace of China's Huangyan Dao" without "approval" from Beijing, Southern Theater Command spokesperson Tian Junli said, according to a statement from the Defense Ministry.

"We sternly warn the Philippines to immediately cease its infringement and provocations,” Tian said.

China claims sovereignty over the island of Huangyan Dao -- also known as Scarborough Shoal or Bajo de Masinloc -- a territory also claimed by the Philippines. The shoal has long been a flashpoint in maritime disputes between Beijing and Manila.