Beijing - China said it sent warplanes into its newly declared maritime air defence zone days after the US, South Korea and Japan all sent flights through the airspace in broadening defiance of rules Beijing says it has imposed over the East China Sea.
China's air force on Thursday sent several fighter jets and an early warning aircraft on normal air patrols in the zone, the Xinhua agency reported, citing air force spokesperson Shen Jinke.
The report did not specify exactly when the flights were sent or whether they had encountered foreign military aircraft.
The US, Japan and South Korea have said they have sent military or coast guard flights through the zone without encountering any Chinese response since Beijing announced its creation last week.
Shen described Thursday's flights as "a defensive measure and in line with international common practices".
Lack of efforts to stop foreign flights
He said China's air force would remain on high alert and will take measures to protect the country's airspace. Chinese officials have said commercial flights are unaffected by the new rules.
While China's surprise announcement last week announcing the zone initially raised some tensions in the region, analysts say Beijing's motive is not to trigger an aerial confrontation but is a more long-term strategy to solidify claims to disputed territory by simply marking the area as its own.
China's lack of efforts to stop the foreign flights - including two US B-52s that flew through the zone on Tuesday - has been an embarrassment for Beijing. Even some Chinese state media outlets suggested on Thursday that Beijing may have mishandled the episodes.
Without prior notice, Beijing began demanding on Saturday that passing aircraft identify themselves and accept Chinese instructions or face consequences in an East China Sea zone that overlaps a similar air defence identification zone overseen by Japan since 1969 and initially part of one set up by the US military.
But when tested just days later by US B-52 flights - with Washington saying it made no effort to comply with China's rules, and would not do so in the future - Beijing merely noted, belatedly, that it had seen the flights and taken no further action.
Zone spans about 1 000km
South Korea's military said on Thursday its planes flew through the zone this week without informing China and with no apparent interference.
Japan also said its planes have been continuing to fly through it after the Chinese announcement, while the Philippines, locked in an increasingly bitter dispute with Beijing over South China Sea islands, said it also was rejecting China's declaration.
The zone covers an area spanning about 1 000km from north to south, above international waters separating China, South Korea, Japan and Taiwan. Alliance partners the US and Japan together have hundreds of military aircraft in the immediate vicinity.
Japanese –controlled islands
Japanese commercial flights have continued to pass through the zone, en route to destinations including Taiwan, Vietnam and Hong Kong.
They initially had notified Chinese authorities of their flights as requested, until early this week, when the Japanese government urged them to stop doing so.
The zone is seen primarily as China's latest bid to bolster its claim over a string of uninhabited Japanese-controlled islands in the East China Sea - known as Senkaku in Japan and Diaoyu in China.
Beijing has been ratcheting up its sovereignty claims since Tokyo's nationalisation of the islands last year.