(CNN) -- On a visit to Japan on Tuesday, Vice President Joe Biden assured his hosts that the United States will express concerns to China over Beijing's recent claim of a large swath of airspace in the region.
The Chinese declaration less than two weeks ago has prompted a war of words between governments and flights through the contested air zone by military planes from the United States, China, Japan and South Korea.
"We, the United States, are deeply concerned by the attempt to unilaterally change the status quo in the East China Sea," Biden said at a news conference alongside Japanese Prime Minister Shinzo Abe.
"I will be raising these concerns with great specificity directly when I meet with the Chinese leadership" on a later leg of his trip, Biden said.
The uneasy situation in the sky over the East China Sea has raised fears that a midair incident could cause circumstances to spiral out of control. It has also fueled concern about how far China is willing to go to pursue its interests in the Asia-Pacific region and push back against U.S. influence.
"The United States has an interest in the lowering of tensions in this vital region, as I believe all the countries in northeast Asia share that same interest with us," Biden said.
China is asking aircraft entering its air defense zone to identify themselves and submit flight plans. U.S. State Department spokeswoman Jennifer Psaki reiterated Monday that Washington recognizes neither the air defense zone nor China's demand to be notified of plans by jets from other nations to fly into the area.
Japan has told its airlines not to comply with the new Chinese demands, but the U.S. government has urged American carriers to follow Beijing's instructions.
The Chinese action, Biden said, raises the possibility of "accidents and miscalculation."
He praised the alliance between the United States and Japan, sayings the U.S. commitment to Japan is critical. He called Japan the cornerstone of stability in the region.
Tokyo and Beijing's bitter dispute over a set of small, uninhabited islands in the East China Sea has already led to frequent tense encounters between the two sides' ships and planes over the past year. Now, China's new air defense zone overlaps significantly with that of Japan and encompasses the disputed islands and the natural resources around them.
"We meet in a moment, Prime Minister, when a new Asia Pacific is emerging, with limitless potential, but also new dynamics, rising tensions and the risk of miscalculation," Biden said.
Geng Yansheng, spokesman for the Chinese Ministry of National Defense, defended China's actions in a written statement.
China's airspace claim, he said, "is a zone of safety, not risks, a zone of cooperation, not competition."
China's actions are justified by what it sees as aggressive moves by the Japanese to lay claim to the disputed territory.
"Japan's actions have seriously harmed China's legitimate rights and security interests, and undermined the peace and stability in East Asia," Geng said.
Without naming the United States, Geng warned third countries about becoming involved in the dispute.
"Other parties concerned should also mind their words and actions, and should not do things to undermine regional stability and bilateral relations," he said. "Other parties should not be incited, or send wrong signals to make a very few countries go further on the wrong track, which will follow the same old disastrous road and undermine regional and world peace."
In addition to the China airspace claim, Biden and Abe discussed ways to fortify U.S.-Japan relations economically and militarily.