Taiwan scrambled a number of fighter jets after China sent more than 30 war planes to the island, it is reported.
China shared footage on state TV channels of missiles and jets mid-flight taking part in a military operation over the waters surrounding Taiwan.
Taiwan's Ministry of Defence also shared footage of military exercises, including live-fire artillery drills in Pingtung, the southernmost province on the island.
The ministry has claimed 10 Chinese warships and 36 military aircraft had been deployed on Wednesday.
It said it was monitoring the situation and was also deploying Taiwanese vessels, aircraft, and land-based missile systems.
According to sources, Chinese naval ships were active off both the east and west coasts of Taiwan, while fighter jets were also flying close to the halfway point of the Taiwanese straight, reports The Sun.
Taiwan's defence ministry said: "We are at the ready keeping our country safe. We stand on the frontlines to protect our country from any threat.
"We neither seek escalation nor instigate disputes. Maintaining the status quo is our solemn mission," it went on, over footage of military exercises.
"Holding the median line, safeguarding our seas and our sovereignty, we have never given in to challenges, and never will."
Foreign Minister Joseph Wu accused China of wanting to exert its power over the East and South China Seas and blockading Taiwan to prevent its allies from providing support.
He said "China has no right to interfere in or alter" Taiwan's democracy or interactions with other nations.
Meanwhile, the Chinese embassy in London has condemned what it called Britain's "irresponsible rhetoric" after Foreign Secretary Liz Truss summoned its ambassador over Beijing's actions towards Taiwan.
Truss summoned Zheng Zeguang earlier on Wednesday, saying China's "increasingly aggressive behaviour" following U.S. House Speaker Nancy Pelosi's visit was threatening peace and stability in the region around Taiwan.
Zheng "firmly rejected & strongly condemned UK side's irresponsible rhetoric about China's legitimate & necessary response to US House Speaker's Taiwan visit" in a meeting with a senior British foreign ministry official, the Chinese embassy said on Twitter.
"Taiwan is an inseparable part of China's territory. No foreign country, UK included, has the right to meddle with the internal affairs of China."
