Formation of the ADIZ in South China Sea (SCS) depended on any threats to air or maritime security, Admiral Sun Jianguo, a deputy chief of staff of the People's Liberation Army said in response to a question at regional security forum Shangri-La Dialogue here.
China has retained its option of establishing the ADIZ if it is stretched in the SCS by US and other powers, he said.
An ADIZ requires all the incoming aircraft, including the civilian airlines, to register with the Chinese authority to fly in the air routes above the islands.
Beijing has been hotly contesting Japanese hold on the Senkaku/Diaoyu islands and has been conducting counter naval patrols. The fighter jets of the two countries came dangerously close in the past to assert their claims.
China so far kept the ADIZ option open in the SCS which if implemented could cause uproar in East Asia as Beijing's claims are strongly opposed by Vietnam, the Philippines, Malaysia, Brunei and Taiwan.
Speculation is rife about the ADIZ as China is developing 2,000 km-long land reclamation project near Spratly Islands, which it calls 'Nansha' also claimed by the Philippines.
Refuting US Defence Secretary Ash Carter's comments yesterday that China's construction projects in the waters raised the risk of "miscalculation or conflict", Sun said China's actions are peaceful and legitimate, calling on other countries to stop trying to "sow discord" over the matter.
"There is no reason for people to play up this issue in the South China Sea," he said.
"China has carried out construction on some islands and reefs in the SCS mainly for the purpose of improving the functions of the relevant islands and reefs, and the working and living conditions of personnel stationed there.
