Yan Fei had just gotten off the phone with China's higher-ups, so he naturally knew their attitude towards him. Otherwise, upon seeing Duan Hongye attacking his Command Center, he almost thought the nation had a new idea in mind! Moreover, when the leader of China Special Duties Unit visited Yan Fei on Dream Island, he had subtly mentioned that if Yan Fei ever found anything off about Duan Hongye, he should immediately prepare to respond and not treat him as a member of the China Special Duties Unit.
Therefore, when Yan Fei noticed that something was definitely off with Duan Hongye, and no other members of the China Special Duties Unit were accompanying him, Yan Fei did not contact Duan Hongye directly. Instead, as soon as Duan Hongye entered the elevator, Yan Fei activated the defense measures. Everything Duan Hongye did and said in the elevator was heard by Yan Fei.