Beijing - US Vice President Joe Biden arrived in Beijing on Wednesday to raise concerns over a Chinese air zone ramping up regional tensions and bolstering ties while also underscoring alliances with Tokyo and Seoul.
His trip, which began in Japan and ends in South Korea follows weeks of a furore after Beijing declared an "air defence identification zone" (ADIZ) covering the East China Sea islands disputed with Japan.
Biden waved from the door of his aircraft before walking down the steps at Beijing airport, where he was greeted by military guards and driven away in a large convoy, an AFP reporter saw.
The decades-old argument between historic rivals Beijing and Tokyo flared after Japan bought some of the islands from their private owners in September 2012.
Since then, China has sent ships and aircraft to nearby waters while Japan has scrambled fighter jets on hundreds of occasions, raising concerns of an unintended clash.
At a joint press conference on Tuesday with Japanese Prime Minister Shinzo Abe, Biden said he would raise Washington's concerns over the air zone "in great specificity when I meet with the Chinese leadership".
"We, the United States, are deeply concerned by the attempt to unilaterally change the status quo in the East China Sea," Biden said.
'For our allies'
A US official said it was especially important "that we continue to amplify our messages that we are and always will be there for our allies", adding that "there is a way for two major powers, in the US and China, to build a different kind of relationship for the 21st century".
Beijing provoked widespread anger late last month by declaring an ADIZ in which all aircraft had to obey Chinese orders or face unspecified "defensive emergency measures".
Washington, Tokyo and Seoul all sent military or paramilitary planes into the zone in defiance of Beijing's rules, while the US reiterated its security pact with Japan.
But American airlines complied with the rules while Japanese airlines quickly stopped doing so under pressure from their government.
US officials told reporters on Tuesday there was "fundamentally no daylight" between the two nations' positions on the ADIZ but declined to answer directly if Washington was comfortable with Japan's response.
The officials said simply that the two sides were "in very close consultation" and the US underscored the importance of "restraint by everybody".
China for its part has accused the US and Japan (both have ADIZs) of double standards, saying the real provocateur is Tokyo.
It also accuses Japan of being unwilling to negotiate by refusing to even acknowledge that a dispute exists over the islands, which Tokyo control but Beijing regards as part of its territory.
An editorial in the state-run China Daily on Wednesday warned that Biden's backing of Japan would undermine his credibility in China.
"Despite trying to present the image of being an impartial mediator, Washington has obviously taken Japan's side," it said.
"He should not expect any substantial headway if he comes simply to repeat his government's previous erroneous and one-sided remarks."
Analysts say that despite the rhetoric the two Asian powers, the world's second and third-largest economies have strong incentives to avoid conflict and China may have been looking to stake out a diplomatic position with the zone.