Beijing's decision to declare an air defense identification zone in an area that includes disputed islands has triggered protests from the United States, Japan and South Korea and dominated Biden's talks in Tokyo on Tuesday.The United States has made clear it will stand by treaty obligations that require it to defend the Japanese-controlled islands, but it is also reluctant to get dragged into any military clash between rivals Japan and China.Biden told Chinese President Xi Jinping he believed Xi was a candid and constructive person."In developing this new relationship, both qualities are sorely needed," Biden said during a meeting in Beijing's Great Hall of the People."Candor generates trust. Trust is the basis on which real change, constructive change, is made."Xi said the international situation and regional landscape were "undergoing profound and complex changes"."Regional issues keep cropping up and there are more pronounced global challenges such as climate change and energy security. The world is not tranquil," he added.Neither made any mention of the air defense zone in remarks before reporters. Biden flies to Seoul on Thursday.As Biden arrived, the official English-language China Daily said in a strongly worded editorial that he "should not expect any substantial headway if he comes simply to repeat his government's previous erroneous and one-sided remarks"."If the US is truly committed to lowering tensions in the region, it must first stop acquiescing to Tokyo's dangerous brinkmanship. It must stop emboldening belligerent Japanese Prime Minister Shinzo Abe to constantly push the envelope of Japan's encroachments and provocations."Under the zone's rules, all aircraft have to report flight plans to Chinese authorities, maintain radio contact and reply promptly to identification inquiries.US, Japanese and South Korean military aircraft have breached the zone without informing Beijing since it was announced on November 23.Japanese and South Korean commercial carriers have also been told by their governments to ignore the rules. Three US airlines, acting on government advice, are notifying China of plans to transit the zone.China has repeatedly said the zone was designed to reduce the risk of misunderstandings, and stressed that since it was set up there had been no issues with freedom of flight for civilian airlines.The Defense Ministry on Tuesday slammed what it said were "distortions" and "mud throwing" over the zone and China's intentions."It is not aimed at any specific country or target, and it certainly does not constitute a threat towards any country or region," ministry spokesman Geng Yansheng said in a statement.Chinese Foreign Ministry spokesman Hong Lei said 55 airlines from 19 countries were cooperating with China's request to report flight plans and identify themselves in the zone.Hong added that China was "willing to maintain dialogue and communication on relevant technical issues with Japan on the basis of equality and mutual respect". He did not elaborate. NERVOUS REGION Beijing's move has added to regional nerves about China's strategic intentions as it presses territorial claims in the South China Sea and ramps up an ambitious military modernization program.Wang Dong, an associate professor of international relations at Peking University, said China's restraint in the wake of flights by US, Japanese and South Korean military aircraft showed China was serious when it said the zone was defensive."However, it would have been very helpful if China had presented a coherent story and a coherent case on the zone from the very beginning, instead of waiting," Wang said.In Tokyo, Biden called on Japan and China to find ways to reduce tensions, repeating that Washington was "deeply concerned" by the announcement of the zone.However, influential Chinese tabloid the Global Times, published by the Communist Party's official People's Daily, noted that Biden had not come down heavily on Japan's side, saying he failed to "sate Japan's appetite" for strong words.White House spokesman Jay Carney said on Tuesday that China's decision was a provocative attempt to change the status quo in the East China Sea.The China Daily said it was obvious Washington had taken Tokyo's side in the dispute."Biden needs to be reminded that Japan holds the key to peacefully solving the East China Sea dispute, because it is the Abe administration's recalcitrant denial of the existence of a dispute that has prevented Beijing and Tokyo from conducting meaningful communication and crisis control," it said.China wants Japan first to acknowledge that a formal dispute over sovereignty exists, experts say, a step that Tokyo has rejected for fear it would undermine its claim over the islands, known as the Senkaku in Japan and the Diaoyu in China."Again, our timely visitor needs to be told: It is Japan that has unilaterally changed the status quo... China is just responding to Japanese provocations."