The patrols followed announcements by Japan and South Korea that their military planes had flown through the zone unhindered by China.
The tit-for-tat flights between China on one side and South Korea and Japan on the other heightened the tensions over the East China Sea where China and Japan are at loggerheads over islands they both claim.
The airspace in the new zone announced by China last week overlaps a similar zone declared by Japan more than 40 years ago. Both zones are over the islands known as Diaoyu in China and Senkaku in Japan.
China has said that noncommercial aircraft entering the zone without prior notification would face “defensive emergency measures.”
China would take “relevant measures according to different air threats” to defend the country’s airspace, Xinhua reported.
In a direct challenge to earlier threats by China that it could take military action against foreign aircraft entering the zone, the United States sent two unarmed B-52 bombers to fly through the airspace for more than two hours overnight Monday. The Chinese military said it had monitored the flight path of the American planes, and China appeared to backpedal from its initial threats of action.