TOKYO (AP) — Japanese and U.S. forces have conducted a joint fighter jet flight over the Sea of Japan, Japan’s Defense Ministry said Thursday, in an apparent response to a Russia-China joint bomber flight while U.S. President Joe Biden was in Tokyo.

The Japan-U.S. joint flight on Wednesday was meant to “confirm combined capabilities of the Japanese SDF and the U.S. forces and to further strengthen the Japan-U.S. alliance," the Joint Staff of the Japanese Self-Defense Force said in a statement. “In order to respond to any emergency, we are taking utmost readiness.”

The flight was also held hours after North Korea fired three missiles, including an intercontinental ballistic missile, toward the sea between the Korean Peninsula and Japan, amid concerns about another nuclear test by Pyongyang. The missiles fell into the waters outside of Japan's exclusive economic zone.

Chinese and Russian strategic bombers conducted joint flights near Japan on Tuesday, Japan’s Defense Ministry said, while Biden was meeting with Japanese Prime Minister Fumio Kishida and their counterparts from India and Australia for the Quad, an Indo-Pacific security and economic coalition meant as a counterweight to China’s growing influence in the region.

Chinese H-6 bombers joined Russian TU-95s over the Sea of Japan and flew to areas over the East China Sea, but did not violate Japanese airspace, said Japanese Defense Minister Nobuo Kishi. Separately, a Russian IL-20 reconnaissance plane was spotted flying off the northern Japanese coast.

The Chinese-Russian joint flight represented an “increased level of provocation” and a threat to the Quad, Kishi said later Tuesday.

China’s Ministry of Defense said the Chinese and Russian militaries carried out joint strategic air patrols above the Sea of Japan, the East China Sea and the western Pacific.

Wednesday’s Japan-U.S. joint flight involved eight warplanes based in Japan, including four U.S. F-16 fighters and four Japanese F-15s, the Japanese Joint Staff said.