Two unarmed US B-52 bombers briefly flew over the disputed Senkakus islands in the East China Sea, defying China's new air defence rules, even as the Chinese air force monitored the flight of the bombers as they flew across its newly-declared "air defence identification zone."
Japan's main airlines also flew through the new air defence zone today without informing Chinese authorities, China's defence ministry said.
The defence ministry said it "detected, identified and monitored" the flight of the giant long-range Stratofortress planes that flew along the zone twice on Tuesday night.
Geng Yansheng, a spokesman of the defence ministry, said the US aircraft flew along the border of the zone in a north-south direction, 200 km east of the disputed `Diaoyu Island', which Japan calls as Senkakus.
"The Chinese government has the will and ability to defend our national sovereignty and security," foreign ministry spokesman Qin Gang said at a press briefing.
"We also have the ability to exercise effective control over the East Sea air defence identification zone," he said.
Japan and the US, on the other hand, accused China of unilaterally attempting to alter the status quo and escalate regional tensions.
The new air zone, announced by China on Saturday, overlaps an air zone set out by Japan and covers disputed islands that are controlled by Japan, according to them.
Japan's major airlines ANA and JAL had initially complied with the Chinese request for their flight plans only to reject it late on Tuesday.
Meanwhile, Japan's parliament enacted a bill on Wednesday to establish a national security council, giving the prime minister greater control over defence issues.
The tensions came amid other military developments in the region.
The Chinese navy's Liaoning aircraft carrier set out for a mission in the South China Sea - where China is engaged in territorial disputes with other nations - in what China described as part of the carrier's "scheduled training".
The defiance from Japan and its ally the United States raises the stakes in a territorial standoff between Beijing and Tokyo over the islands and challenges China to make the next move, experts said.
The islands, known as Senkaku in Japan and Diaoyu in China, have been a source of severe tension between the two nations for months.
While the zone is outside China's territorial airspace, the Chinese defence ministry has said its establishment had a sound legal basis and accorded with common international practices.
Other countries, including the United States, Japan and South Korea, have similar zones but only require aircraft to file flight plans and identify themselves if those planes intend to pass through national airspace.
In addition, China sent its sole aircraft carrier on a training mission for the first time into the oil-and gas-rich South China Sea on Tuesday.
China claims almost the entire South China Sea, conflicting with claims from Taiwan, Malaysia, Brunei, the Philippines and Vietnam.