The Pentagon's announcement that two B-52 bombers breached China’s newly established air-defense identification zone, or ADIZ, over the East China Sea drew heavy criticism from the Chinese public on Wednesday, with several commentators also registering disapproval over a lack of immediate response from the Chinese government.

The unarmed B-52 airplanes took off from Andersen Air Force Base in Guam and entered the ADIZ at about 7 p.m. EST on Monday, in a blatant challenge to China's latest move claiming disputed territory as its own. China had earlier threatened military action against aircraft entering the protected space without notifying Chinese authorities, but Beijing had not officially responded to the incident, although the B-52s refused to inform China about the flight, news reports said.

“If the air defense zone is just a temporary, spoken thing, without means to handle other countries provocatively entering without permission, then we’d be better off not setting it up, because it’s completely unnecessary,” Liu Zhuming, a commentator based in the southwestern city of Chongqing, wrote on his Sina Weibo microblog, the New York Times reported.

Ni Fangliu, a Chinese historian and journalist, wrote on a microblog account that China “will face international ridicule” if the military fails to do anything against an aircraft entering the protected space, the Times reported.

The Pentagon said on Tuesday that it had sent B-52 bombers over the ADIZ, adding that the flights were “uneventful” and were previously planned as part of a training program, the Washington Post reported.

China on Saturday had declared the no-fly zone, which covers a portion of the East China Sea and includes a set of disputed islands known as Senkaku in Japan and Diaoyu in China.

The islands have long been a flashpoint for territorial rows between the two Asian nations, but tensions escalated in September 2012, when the Japanese government announced the signing of a contract worth 2.05 billion yen ($26 million) to buy three of the five main islands from its private owner. Since then, Chinese patrol ships and surveillance planes have frequented the waters around the islands.

PLA Daily, the official newspaper of China's military, had said before the B-52 flights that the ADIZ calls for strong defense capabilities.

“Now, we already have those capabilities, so setting up the air defense zone is only logical,” the paper said, according to the Times.