The announcement by China’s air force that it had sent fighters and an early-warning aircraft to patrol the zone came just a few hours after Japan and South Korea, following the U.S.’s lead, said their military aircraft had flown into the zone without notifying Beijing over the past few days, and would continue to do so.

The U.S. challenged the zone’s credibility on Tuesday by sending in two B-52 bombers without informing Chinese authorities, who had warned when they declared the zone on Saturday that such incursions would be met with unspecified “defensive emergency measures.”

China’s move to enforce an air-defense zone has several countries in the region concerned. The WSJ’s Deborah Kan speaks to Scott Harold of RAND Corp., a global think tank, on why China may be playing the wrong hand in its play for islands in the East China Sea.

The conflicting signals from Beijing highlight the challenge the Chinese leadership faces as it tries to contain the international fallout from its surprise decision to establish the zone, without appearing weak in front of an increasingly nationalistic domestic audience.