Taiwan’s latest military exercise began on Tuesday with a simulated attack on coastal bases by Chinese warplanes hypothetically launched from the Liaoning, currently the only functional aircraft carrier operated by the People’s Liberation Army Navy.

According to the South China Morning Post, the lively exercise employed a Taiwanese combat support ship called Panshi to stand in for the Liaoning. According to Taiwan News, the drill was realistic enough to frighten some local residents into thinking they really were under attack by China.

The real Liaoning has been known to sail through the Taiwan Strait, attracting a good deal of attention from the Taiwanese air force and navy. While its appearance is intimidating, the actual combat ability of the Chinese ship is a matter of much debate, not least because China has a pronounced shortage of pilots who can fly off the relatively primitive carrier. The PLA is working hard on recruiting more pilots and putting a second, more advanced aircraft carrier through sea trials.

The Taiwanese drill was intended to “strengthen the military’s ability to withstand a coordinated air and electronic attack from the PLA” and simulate both bomber interception and a retaliatory strike on a Chinese carrier battle group.

Asia Times reported the drill specifically simulated air raids and electronic interference targeting Chiashan Air Base and “other key military installations along the island’s east coast.” That would be the coast facing away from mainland China and toward the valuable contested islands of the East China Sea, implying the scenario for the wargame was not an all-out Chinese invasion of Taiwan but an East China Sea conflict.

Chiashan Air Base would be a very tough nut for China to crack. The Diplomat described it in September 2014 as a “military city built inside a hollowed-out mountain” with room for two hundred fighters. The base is protected by rapid-fire cannon and surface-to-air missiles.

“With ten blast doors that exit out to multiple runways via a long taxiway that can itself be used as an emergency runway, it may be the toughest airbase ever built,” The Diplomat mused.

In the age of hyper-warfare, it is not necessary to blow an airbase up to shut it down, which explains why the Taiwanese drill put so much emphasis on electronic warfare. Asia Times noted Taiwanese prosecutors are currently working a case involving the theft of sensitive data about the electronic warfare capabilities of a Taiwanese frigate. There are suspicions the information was passed along to Chinese spies.

The South China Morning Post relayed speculation that Tuesday’s drill and several previous exercises over the past week following Taiwan’s National Day commemoration are building up to a major joint drill with the United States, simulating operations in both the Taiwan Strait and the South China Sea. The Taiwanese Defense Ministry dismissed these reports as “sheer speculation.”