Chinese naval vessels and military aircraft encircled Taiwan on Thursday in a military drill that Beijing dubbed a "strong punishment" for the self-ruled island.
The war games come just days after Taipei swore in its new leader Lai Ching-te, who vowed to defend democracy during his inauguration.
The two days of drills are part of an escalating campaign of intimidation by China that has seen it carry out a series of large-scale military exercises around Taiwan in recent years.
The latest show of force is a "strong punishment for the separatist acts of 'Taiwan independence' forces," China's military said as the drills got underway.
China – governed by the Communist Party since 1949 – claims Taiwan as part of its territory and has vowed to bring the island under its rule, by force if necessary.
Thursday and Friday's drills involve aircraft and ships surrounding the island to test their combat capabilities, China's People's Liberation Army (PLA) said.
Taiwan responded by deploying air, ground and sea forces, with the island's defense ministry vowing to "defend freedom."
A Taipei spokesperson also condemned China's "provocative military behavior."
Earlier this week, Taiwan's new leader Lai said: "In face of the many threats and attempts of infiltration from China, we must demonstrate our resolution to defend our nation," while hailing a "glorious" era of democracy.
China warned of strong reprisals to Lai's speech, in which he also vowed to continue building Taiwan's defense capabilities.
It had previously branded Lai a "dangerous separatist" who would bring "war and decline" to the island.
The drills, which began at 7:45 a.m. (11.45 p.m. GMT Wednesday), are taking place in the Taiwan Strait and to the north, south and east of the island, PLA Eastern Theater Command Naval Colonel Li Xi said.
As the "Joint Sword-2024A" drills were launched, commentary on state Chinese broadcaster CCTV declared them "a powerful disciplinary action" against Taiwanese separatism.
China's military put out a series of posters touting what it called its "cross-strait lethality." They featured rockets, jets and naval vessels next to a blood-stained text.
"The weapon aimed at 'Taiwan independence' to kill 'independence' is already in place," it declared.
Beijing, which split with Taipei at the end of a civil war 75 years ago, regards the island as a renegade province with which it must eventually be reunified.
China has stepped up pressure on the democratic island of 23 million people, periodically stoking worries about a potential invasion.
A Chinese military expert told CCTV that the drills were partly aimed at rehearsing an economic blockade of the island.
Zhang Chi, a professor at Beijing's China National Defense University, said the drills aimed to "strangle" Taiwan's critical Kaohsiung port to "severely impact" its foreign trade.
They would cut off "Taiwan's lifeline of energy imports" as well as "block the support lines that some U.S. allies provide to 'Taiwan independence' forces," he added.
The last time China announced similar military exercises around Taiwan was in August last year after Lai, then vice president, stopped over in the United States on his way to Paraguay.
Those drills also tested the PLA's ability "to seize control of air and sea spaces" and fight "in real combat conditions," according to state media.
They followed April drills that simulated the encirclement of the island, launched after Lai's predecessor Tsai Ing-wen met then-U.S. House Speaker Kevin McCarthy in California.
China also launched major military exercises in 2022 after Nancy Pelosi, then the speaker of the U.S. House of Representatives, visited Taiwan.
World powers are keen to see as much stability as possible between China and Taiwan, not least because of the vital role the island plays in the global economy.
The Taiwan Strait is one of the world's most important maritime trade arteries, and the island itself is a major tech manufacturer, particularly of vital semiconductors – the tiny chips used in everything from smartphones to missile systems.
The United States switched its diplomatic recognition from Taiwan to China in 1979 but remains the island's most important ally and supplier of military hardware.
U.S. President Joe Biden has said he does not support Taiwan's independence but also that he would back sending forces to defend the island. The official U.S. position on intervention is one of ambiguity.
The United States did not give an immediate official response to the drills.
U.S. Lieutenant General Stephen Sklenka, speaking in Canberra, described the exercises as "concerning" but not unexpected.
