Tensions in northeast Asia escalate as China rejected South Korea's demand to take corrective measures and redraw a newly declared air defense identification zone (ADIZ) that Beijing had unilaterally set last Saturday. Beijing claims all aircraft entering the zone is obligated to report a flight plan and identification, and to obey orders from Chinese authorities. If not, transiting air traffic could face "defensive emergency measures." That zone includes Ieodo Island, currently controlled by South Korea.
"Although China has always denied it, they want to be a hegemonic power. They're showing that ambition of gradual expansion in this region and this, a serious issue, is not something to be taken lightly," said Lee Jung-Hoon, professor of international relations at Yonsei University in Seoul.
The newly claimed zone also includes a set of long disputed islands claimed by Japan, China and Taiwan – known as Diaoyu in China and Senkaku in Japan.
In defiance of Beijing's claims, South Korean and Japanese officials on Thursday said both have flown planes for surveillance over the zone this week without notifying the Chinese authorities. The United States, calling the move a "destabilizing attempt to alter the status quo in the region," had also flown a pair of unarmed B-52 bombers earlier in the week.
China said it's monitoring the flights. "China identifies any aircraft within the ADIZ. So, China must note the relevant situation you mentioned," China's foreign ministry spokesman Qin Gang replied when asked about Wednesday's South Korean military flight in the zone.
Vice President Joe Biden is expected to raise concern during a visit to the three northeast Asian countries next week.
Meanwhile Australia has summoned the Chinese ambassador to express Canberra's concern about the sudden zone declaration. Foreign Minister Julie Bishop said she is standing by her criticism of the new zone.
"Australia has appropriately raised its concerns privately with the ambassador, and I've raised it publicly to assure the Australian people that the Australian government is continuing this policy of being opposed to unilateral action that could increase the tensions in this disputed territorial zone," Bishop told reporters.
China's new zone also includes intersecting claims in the South China Sea with Taiwan, the Philippines, Malaysia, Brunei and Vietnam.
"China seems still trapped in this cold war mentality that the U.S. is trying to encircle China. Yes, they are upset with the missile defense system. Yes, they aren't happy with the U.S. making friends with Japan, or countries like Vietnam that they consider to be potential hostile entities," Lee pointed out. "To Beijing, maybe this is a defensive posture but from the outside world, this is a very physical, aggressive approach."
AP contributed to this story.