It could have been just another routine military drill with the pseudo enemy's jets retreating. But then the pilots of the People's Liberation Army were caught off guard by chatter over the radio - in English.
By the time they had figured out that they had to confront a third party, their field command - an early-warning plane - had already been shot down, the PLA Daily reported.
Analysts said the inclusion of an English-speaking third party in PLA drills was aimed at sending a message that the Chinese military is preparing for possible intervention by the United States if China clashes militarily with neighbouring countries over territorial disputes.
The "third party" was a surprise scenario added to the drill to strengthen the air force's real combat response capability, the army newspaper said.
The drill took place early last month. As a battle between the PLA air force and its pseudo opponent, the "blue army", reached its climax, the PLA pilots suddenly heard in English over the radio: "Target on a radial 180.60." Followed by "Roger," the PLA Daily reported.
"Who is that? Why is there a foreign language?" some PLA pilots asked, according to the newspaper.
The shooting down of the "red army" airborne command centre forced its air force land commander to withdraw all fighter jets and change strategy to deal with the crisis, it reported.
"The 'third party force' was another surprise scenario we provisionally added to the drill with the aim of making our training more like real combat," the daily quoted drill director Jing Jianfeng as saying.
Ni Lexiong , the director of the sea power and defence policy research institute at the Shanghai University of Political Science and Law, said: "The 'third party' scenario simulated how the PLA would have to react if it was attacked by both the Japanese army and the US air force.
"The PLA report was also aimed at letting Japan and other Asian countries know that the PLA is prepared for all possible military clashes over territory in the East and South China seas."
Beijing-based naval expert Li Jie said the appearance of a "third party force" would become common in PLA training.
The drill was a good example of the PLA's ability to meet the goal of "being prepared for real combat and for victory" which party chief Xi Jinping had demanded," Li said.
Xi reiterated his call for the army to enhance its fighting capabilities through real combat training after he became chairman of the Central Military Commission in November.