22 of the planes reportedly crossed the so-called median line in the Taiwan Strait that separates mainland China from self-governing Taiwan.
“The military is closely monitoring the situation and has assigned aircraft, naval vessels and land-based robotic systems to respond,” Taiwan’s foreign ministry said in a statement.
In recent years, China has increased pressure on Taiwan, with repeated threats and Chinese warplanes flying towards the island.
On Sunday, the Chinese military announced that it is on high alert to “protect national sovereignty and security.” The statement came after an American and a Canadian warship sailed through the Taiwan Strait.
Similar passages happen regularly and are regarded by Beijing as provocations. The law of the sea allows passage in international waters, but China considers itself entitled to both the strait and Taiwan itself.
The United States and Vietnam warn in a joint statement against the “use of threats or force” in the South China Sea. The countries also express their “unwavering support” for a peaceful solution and “unhindered legal trade” in the area.