China and Russia conducted a joint military air patrol over the seas of Japan and eastern China on Tuesday, prompting South Korea to deploy fighter jets as a precaution.
China's official Xinhua news agency, citing China's Defense Ministry, confirmed that "the two militaries conducted their sixth joint air patrol, in accordance with the annual plan for military cooperation" between Beijing and Moscow.
Xinhua did not give any details about the nature, route and location of the planes involved in the patrol over these vast maritime expanses between the Korean peninsula, Japan, China and Taiwan.
For its part, the South Korean military announced the launch of fighter jets "after 4 Russian and 4 Chinese aircraft entered the air defense identification zone of Seoul."
"We have deployed fighters from the air force to take tactical action in preparation for an emergency," the Seoul Joint Chiefs of Staff said, noting that Russian and Chinese aircraft had not violated South Korean airspace.
State Department spokesman Vidant Patel noted that the United States is committed with Japan and South Korea on a "free and open Indo-Pacific zone," adding that the allies were on alert "for any action likely to be considered destabilizing or dangerous."
An air defence zone is a large area unilaterally defined by States, in which foreign aircraft are required to identify themselves for reasons of national security.
South Korea supported Western sanctions imposed on Russia after the war on Ukraine began on February 24, 2022, and sent humanitarian aid to Kiev.
China and Russia strengthened their diplomatic, commercial and military ties more than 10 years ago, continuing after the war in Ukraine.
Beijing, which maintains its neutrality on the Ukraine conflict, calls for respect for the sovereignty of countries but has never condemned Russia's "military operation".
At the end of May, Chinese President Xi Jinping told Russian Prime Minister Mikhail Mishustin, who was visiting Beijing at the time, that the two countries affirmed "unwavering support for each other on issues related to each other's core interests and enhanced cooperation in multilateral forums."
Russia and China should "push cooperation in various fields to higher levels" and "raise the level of economic, trade and investment cooperation", he said.
In February, Beijing issued a document for a "political settlement" of the conflict in Ukraine, which Western countries believed could enable Russia to keep large parts of the territory it seized from Ukraine under its control.