In a move that has heightened tensions with Japan and the United States, the Chinese Defence Ministry announced over the weekend the creation of an “air defence identification zone” (ADIZ), covering much of the East China Sea, including the Diaoyu/Senkaku islands that have been at the center of a bitter dispute between Beijing and Tokyo.

The air defence zone announced by China overlaps Japan’s own ADIZ. The Obama administration immediately criticised the Chinese move and indicated that the US would ignore the Chinese zone. Washington reiterated that the US-Japan Security Treaty will apply if war breaks out between China and Japan over the disputed East China Sea islands.

Underscoring the potentially explosive implications of the Chinese announcement, the Chinese air force sent early warning aircraft and fighters on a sweep of the defence zone, prompting Japan to scramble its own F-15 fighters.

Any aircraft entering the ADIZ will trigger alerts to the Chinese air force and air defence system. According to the Chinese Defence Ministry statement, aircraft are expected to provide their flight plans, indicate their nationality, and maintain radio communication.

“China’s armed forces will adopt defensive emergency measures to respond to aircraft that do not cooperate in the identification or refuse to follow the instructions,” the statement added.

The move came less than two weeks after the idea was leaked to the media by the Chinese military. It is a response to the growth of military tensions in the region, precipitated by the Obama administration’s so-called “pivot to Asia,” which is centrally aimed at diplomatically and militarily isolating and encircling China and checking its challenge to American dominance in East and South Asia. A central aspect of the “pivot” is support for Japan’s re-militarisation.

As part of this anti-Chinese strategy, Washington has worked to stoke up long-simmering territorial disputes in the East China and South China seas between China and nearby countries such as Japan, Vietnam and the Philippines.

Japan has for some time maintained its own air defence zone in the region, resulting in the frequent scrambling of Japanese fighter jets against Chinese aircraft flying over international airspace near the Okinawa island chain. The Japanese government of Prime Minister Shinzo Abe has even threatened to shoot down Chinese drones, prompting warnings from Beijing that it would consider such a development an “act of war.”

In a statement, the Japanese Foreign Ministry declared the Chinese air defence zone to be “totally unacceptable and extremely regrettable, as it includes the Japanese territorial airspace over the Senkaku Islands, an inherent territory of Japan.” The statement continued: “Unilaterally establishing such airspace and restricting flights in the area is extremely dangerous, as it may lead to miscalculation in the area.” Japan lodged a protest with China, which Beijing promptly rejected.

Just a week ago, Japan concluded a large-scale military exercise in the Okinawa region, employing both land-based anti-ship missiles and 350 warplanes to stimulate an attack on Chinese ships. Two weeks prior to that, a major Chinese naval exercise in the same region, the “Mobile 5,” simulated penetrating the “First Island Chain,” which stretches from Japan to Okinawa, Taiwan and the Philippines. The exercise also included maneuvers on the high seas against a potential enemy fleet.

US Secretary of State John Kerry on Saturday denounced the establishment of the Chinese ADIZ, saying, “The United States is deeply concerned about China's announcement that they’ve established an ‘East China Sea Air Defense Identification Zone.’” He declared that the US and its allies had the right to “freedom of flight” and “freedom of navigation”, which practically is to deploy warships or aircraft just outside of China’s territorial waters and airspace.

“We urge China not to implement its threat to take action against aircraft that do not identify themselves or obey orders from Beijing,” Kerry continued, as “freedom of over-flight and other internationally lawful uses of sea and airspace are essential to prosperity, stability, and security in the Pacific.”

Chinese President Xi Jinping, who has close connections with the military, has in recent months ordered Chinese forces to apply the same right to “freedom of flight” to Japan and to regions near US military bases in East Asia. Chinese military aircraft have with increasing frequency been using international airspace near the Okinawa island chain to enter the West Pacific.

Chinese electronic surveillance ships reportedly appeared in waters near Hawaii for the first time to collect communications data from the US Pacific Fleet.

China has never previously maintained an ADIZ, even though the US and allies such as Japan, Taiwan and South Korea have had such systems in place for decades. After having invested enormous resources to establish a modern air force, the Chinese regime now considers the establishment of such a defence zone a military necessity.

China announced the air zone only one day after it test-flew its Sharp Sword stealth drone bomber, making it the fourth country to develop such technology after the US, France and Britain.

The Pentagon reacted aggressively to the Chinese ADIZ announcement. Secretary of Defence Chuck Hagel reiterated the official position that the US-Japan security alliance covers the Senkaku islands. This implies that the United States would automatically become involved on the side of Japan if a war broke out with China. “We view this development as a destabilising attempt to alter the status quo in the region,” Hagel warned Beijing.

Hagel insisted the US would simply ignore the rules China proclaimed for its air defence zone. “This announcement by the People’s Republic of China will not in any way change how the United States conducts military operations in the region,” he said.

If the American military proceeds on the basis proclaimed by Hagel, the risk will increase of confrontations, clashes or outright war between the US and China.