China is conducting a three-day military drill, rehearsing the encirclement of Taiwan.
Beijing, which regards Taiwan as a breakaway province, stated that this operation was a "stern warning" to Taiwan's government.
The drills started shortly after President Tsai Ing-wen returned from her visit to the United States.
According to the Taiwanese Defence Ministry, 71 Chinese military planes and nine ships crossed the unofficial dividing line between the two territories, known as the Taiwan Strait median line.
During the exercise, one ship fired a round as it sailed close to Pingtan island, which is China's nearest point to Taiwan.
Chinese state media announced that the drills would involve long-range rocket artillery, naval destroyers, missile boats, air force fighters, bombers, jammers and refuellers, and would "simultaneously organise patrols and advances around Taiwan island, shaping an all-round encirclement and deterrence posture."
Despite China's claim over Taiwan, the latter considers itself a self-governing nation with its own constitution and leaders.
China views Taiwan as a province that has separated from its territory and that will eventually be brought under Beijing's control, even if this requires the use of force.
President Xi Jinping has stated that "reunification" with Taiwan is a necessary goal.