Plane spotters monitoring the airwaves around Taiwan said they captured the exchange on the aeronautical emergency frequency 121.5 MHz at 9:20 a.m. Taipei time, on a morning that saw 17 warnings sent to PLA warplanes in the space of six hours.

Taiwan’s Ministry of National Defense later confirmed that a total of 28 Chinese military planes had flown into Taipei’s air defense identification zone (ADIZ), marking the largest number of single-day incursions on record since 25 warplanes were detected in the ADIZ on April 12.

The radio intercept sent to Newsweek begins with a standard broadcast by a Taiwanese radio operator: “This is the Republic of China [ROC] Air Force. The Chinese military aircraft flying at 6,500 meters in Taiwan’s southwestern airspace: You have entered our airspace and are affecting aviation safety. Turn around and leave immediately.”

The operator adds to the message with a seldom heard caution: “The consequences of any accident are yours alone.”

According to a transcript of the radio correspondence, a Chinese pilot responded: “This is the People’s Liberation Army Naval Air Force conducting a routine mission.”

No radio exchanges between the two followed, but it was not the first time a PLA pilot had engaged with ROC Air Force personnel.

According to publicly available data released by Taiwan’s Defense Ministry, China set a monthly record for ADIZ incursions in April, flying a total 107 sorties into the area. Before Tuesday’s operations, May had seen a significant drop in ADIZ forays.

The resumption of military activity in the Taiwan Strait comes after President Joe Biden led G7 and NATO leaders in rebukes of Beijing’s policies in trade, technology and human rights, among other areas.

The G7 communique released on Sunday was notable for its emphasis on peace and stability across the Taiwan Strait. The leaders also raised concerns about developments in the East and South China seas, where the Chinese military has engaged in increasingly coercive behavior towards its neighbors.

Before the large-scale incursion on June 15, there had been a lull in China’s “gray zone” activity around Taiwan, which lasted around 10 days.

The relative quiet was likely the result of the Chinese government’s attempt to recalibrate its diplomatic and military actions following a number of U.S.-led joint statements in support of Taiwan’s security, said Su Tzu-yun, a senior analyst at the Institute of National Defense and Security Research in Taipei.

Su believes the joint statements were effective to an extent. “But it would probably be an overinterpretation to expect them to completely deter China’s military behavior,” he told Newsweek.

The researcher, who said Beijing’s use of the PLA was more political than military, concluded that China’s nationalist domestic audience would have demanded a stern response to the communiques by the G7 and NATO.

“But I would consider it an overreaction on Beijing’s part. It doesn’t benefit Beijing,” he added. “Responding with hard power only proves the China threat theory.”