"The fighters of the Eastern zone of the PLA combat command observed the entire flight of the US aircraft," Shi said in a statement published on WeChat.
US vessels have recently been staging provocations that "undermine peace and stability" in the Taiwan Strait and pose threats to regional security, the spokesman added.
Shi also said that Chinese troops always maintain a high level of combat readiness and defend state sovereignty and territorial integrity.
On April 16, the Japan-based missile destroyer USS Milius of the US navy crossed the Taiwan Strait after Chinese naval forces conducted military drills in the vicinity of the island a week earlier.
The situation around Taiwan recently escalated once again after Taiwanese President Tsai Ing-wen's meeting with US House Speaker Kevin McCarthy earlier in April, with Beijing starting massive three-day military exercises near the island in what it called a "warning" for Taiwanese separatists and foreign powers.
Taiwan has been governed independently from mainland China since 1949. Beijing views the island as its province, while Taiwan — a territory with its own elected government — maintains that it is an autonomous country but stops short of declaring independence. Beijing opposes any official contacts of foreign states with Taipei and considers Chinese sovereignty over the island indisputable.