Defying China’s announcement it was creating an air defense identification zone in the East China Sea, aircraft of the Self-Defense Forces and Japan Coast Guard have continued flying into the zone without informing Beijing ahead of time, Chief Cabinet Secretary Yoshihide Suga said Thursday.

Suga didn’t elaborate, but he did say Japan detected no reaction from China while the operations were under way.

“Japan has conducted patrol activities by flexibly mobilizing P-3Cs (anti-submarine airplanes) and destroyers around Japan, including the East China Sea. We have continued our patrolling activities just as we have done before China set up its ADIZ” last week, Suga said.

“We will never change this for the sake of China,” he stressed.

The U.S. has also expressed deep concern about the Chinese move, sending two unarmed B-52 strategic bombers through the zone without prior notice, despite China’s demand that it be told of plans to fly military aircraft there.

Japan is “firmly determined to defend its territorial land, sea and air space” against China’s attempt to change the status quo by coercion, Suga said.

Japan and the U.S. have said they will ignore China’s declaration of the zone and the rules it is trying to impose there.

China has said it may take “defensive measures” against violations.

Tokyo and Washington both say the ADIZ violates the freedom of air traffic over the high seas as established by international law. South Korea has also expressed its displeasure.

Earlier in the day, Suga met U.S. Ambassador Caroline Kennedy for the first time.

During their meeting in the prime minister’s office, they agreed that the U.S. and Japan will “more closely cooperate with each other” in dealing with issues related to China’s new ADIZ, according to Suga.

Suga told Kennedy that China’s attempt to establish the air zone is “very dangerous,” according to government officials.