Aircraft from South Korea’s military and Japan’s Self-Defence Forces have carried out flights through China’s newly established Air Defence Identification Zone (ADIZ) in the disputed East China Sea, with both countries on Thursday indicating they will defy China’s plans to bolster its control over the contested region.

South Korea’s military said it conducted a surveillance flight through the zone “without informing the Chinese authorities”, the Seoul-based Yonhap news agency reported, adding that the flight was “a clear sign” that the government would not follow China’s regulations.

Earlier this week, Seoul expressed “regret” over China’s announcement, with the ADIZ overlapping with parts of the South Korean air defence zone in the region.

Several countries, such as South Korea and Japan, have already set up similar zones, which are pre-defined areas in international airspace within which a country monitors and tracks aircraft that are heading towards its territorial airspace.

After Saturday's surprise announcement brought concerned responses from the U.S., Japan and South Korea, China on Thursday issued a muted reaction to the South Korean flight.

Asked about the South Korean flights, the Foreign Ministry here only said China would “identify any aircraft within the ADIZ in accordance” with Saturday’s announcement, which, however, also warned of “emergency” responses to aircraft that failed to submit their flight plans.

On Tuesday, the U.S., too, made clear it would defy China’s demand that all aircraft notify authorities before entering the ADIZ, with two B-52 bombers carrying out at a pre-scheduled training mission and

flying through the zone for two and a half hours without notifying

China. China said on Wednesday it “identified” the aircraft, although it did not appear to take further steps.

China’s muted response brought criticism from some sections of the State media, with the nationalistic tabloid the Global Times saying in a Thursday editorial that China “failed in offering a timely and ideal esponse” and risked “undermin[ing] the image of our military forces”.

“Chinese authorities must make speedy reactions to various emergencies and challenges,” the editorial said.

On Thursday, officials in Tokyo said Japanese Self-Defence Forces had also flown through the zone – parts of which overlap with Japan’s ADIZ —without notifying Beijing, and “no response was detected”.

The ADIZ includes the disputed Diaoyu or Senkaku islands in the East China Sea, over which both countries have competing claims. In recent months, naval vessels from China and Japan have had run-ins in the aters off the islands, while Japan recently threatened to shoot down Chinese drones over the area.

Japanese Chief Cabinet Secretary Yoshihide Suga said the government was “conducting surveillance activities as usual even after the Chinese notification". Earlier this week, Japan warned that the move ight trigger “unexpected” incidents and raise the likelihood of an incident between the two air forces.

Chinese Defense Ministry spokesman Yang Yujun on Thursday hit out at the Japanese government for “tarnishing other countries without reflecting on their own deeds”. He said Japan had established an ADIZ in 1969, so it had “no right at all to make irresponsible remarks”.

Responding to Japanese Prime Minister Shinzo Abe’s statement calling for China to retract the announcement, he said, “Should the decision be retracted, we ask the Japanese side to revoke its ADIZ first, we will then consider their demand 44 years later”.

The ADIZ issue is expected to figure prominently during next week’s visit by U.S. Vice President Joe Biden to South Korea, China and Japan. Japanese officials told the Kyodo news agency that the government also planned to raise the issue during an ASEAN regional summit that is scheduled to be held in Tokyo next month.

More In: World | International | News