South Korea's defence chief said the country is considering expanding its air defense identification zone to include its southern islands and an underwater rock, NHK World reported on Friday. The new air defense zone would overlap those of Japan and China. South Korean Defense Minister Kim Kwan-jin explained the plan at a parliamentary defense committee meeting on Thursday. Kim said the government is considering incorporating areas around the southern islands of Marado and Hongdo into the zone. South Korea's airspace over those islands overlaps Japan's air defense identification zone.