China 'monitored' US B-52 air zone flights: ministry

China "monitored" US B-52 bomber flights in its newly-declared air defence identification zone, the defence ministry said Wednesday, in an assertion of its authority that stopped short of threatening direct action, AFP reports. The flight of the giant, long-range Stratofortress planes was a clear warning that Washington would push back against what it considers an aggressive stance by Beijing in the region. The Air Defence Identification Zone (ADIZ) in the East China Sea includes Japan-administered islands at the heart of a tense dispute between the two neighbours. Beijing's controversial demand that aircraft submit flight plans when traversing it triggered a storm of diplomatic protest. The Pentagon said it did not comply with the Chinese rules. But, in a statement, Beijing's defence ministry spokesman Geng Yansheng said: "The Chinese military monitored the entire process, carried out identification in a timely manner, and ascertained the type of US aircraft. "China is capable of exercising effective control over this airspace," Geng added. The statement, China's first official response to the US action, did not include any expression of regret or anger at the flight, and appeared to be relatively non-confrontational, while re-iterating Beijing's claim of control. Under the rules declared by China, aircraft are instructed to provide a flight plan, clearly mark their nationality and maintain two-way radio communication to allow them to respond to identification queries from Chinese authorities. Any that do not comply can face "defensive emergency measures", says Beijing, which portrays the zone as in line with international practice. State-run media say the ADIZ extends as close to Japan as Tokyo's own zone approaches China. Japan, the United States and several other governments rejected the zone after it was announced over the weekend, and the US State Department reiterated on Tuesday that China's action appeared to be an attempt to "unilaterally change the status quo in the East China Sea". The B-52 flight was also a signal of US support for Japan, with which Washington has a security pact, and its new ambassador to Tokyo Caroline Kennedy said Wednesday: "The Japanese can see every day that America is here for them as a partner in the defence of Japan." The bombers -- which were unarmed -- took off from Guam on Monday on a scheduled flight in what US defence officials insisted was a routine exercise dubbed "Coral Lightning Global Power Training Sortie". Japanese airlines, under pressure from Tokyo, stopped following China's new rules on Wednesday after initially complying. Chinese officials and state media have accused Japan and the US -- which both have ADIZs of their own -- of double standards. In a commentary Tuesday, the official Xinhua news agency said they were "indulging in the trick of calling white black". Chinese foreign ministry spokesman Qin Gang this week re-iterated Beijing's oft-stated position that it was not at fault for heightening friction. "The current tensions regarding the Diaoyu islands are completely caused by the Japanese side," he said at a regular press briefing. The waters surrounding the remote, uninhabited outcrops known as the Diaoyu islands in China and the Senkakus to Japan are believed to be rich in oil, natural gas, fish and other resources. The territorial dispute, which has simmered for decades, escalated in September 2012 when Japan purchased three of the islands from private owners. It portrayed the move as an attempt to avoid a more inflammatory step by a nationalist politician, but Beijing accused Tokyo of changing the status quo. Since then it has sent ships and planes to the islands in a show of force, prompting Japan to scramble fighter jets 386 times in the 12 months to September. The close encounters have raised fears of an accidental clash. But analysts stress that both China and Japan have strong incentives to avoid armed conflict. The two share significant business ties as the world's second- and third-largest economies. Beyond the East China Sea, Beijing has taken an assertive approach to a number of territorial disputes, particularly in the strategic South China Sea. In response to China's growing military might and influence, the United States has sought to shift its strategic focus to Asia, planning to expand America's military presence across the Pacific.