Assault helicopters launched missiles and fighter jets dropped bombs on targets at sea, while tanks and missile trucks fired from a beach to deter a simulated invading force.
“We want the world to see our determination and efforts to protect our country.” President Tsai Ing-wen said, observing the exercise in a helmet and green military uniform.
The drill was part of a five-day annual exercise that ends Friday.
China regards Taiwan as a breakaway province that is part of its territory. The self-governing island of 24 million people lies 160 kilometers (100 miles) off China's southeast coast across the Taiwan Strait.