The large-scale Chinese deployment came as Beijing increased preparations for a potential blockade or military action against Taiwan that have stirred growing concern among military leaders, diplomats, and elected officials in the U.S., Taiwan's key ally.
In a memo last month, U.S. Air Force Gen. Mike Minihan instructed officers to be prepared for a U.S. -China conflict over Taiwan in 2025. As head of the Air Mobility Command, Minihan has a keen understanding of the Chinese military and his personal remarks echo calls in the U.S. for heightened preparations.
Taiwan's Defense Ministry said 20 Chinese aircraft on Tuesday crossed the central line in the Taiwan Strait that has long been an unofficial buffer zone between the sides, which separated during a civil war in 1949.
China claims the island republic as its own territory, to be taken by force if necessary, while the vast majority of Taiwanese are opposed to coming under the control of China's authoritarian Communist Party.
Taiwan's armed forces ``monitored the situation ... to respond to these activities,'' the Defense Ministry said Wednesday.
That announcement came as NATO Secretary-General Jens Stoltenberg warned that China's growing assertiveness and collaboration with Russia pose a threat not only to Asia but also to Europe.
On a visit to Japan on Wednesday, Stoltenberg said China is increasingly investing in nuclear weapons and long-range missiles without providing transparency or engaging in arms control talks.
Stoltenberg earlier criticized China for ``bullying its neighbors and threatening Taiwan'' and stressed the need for Japan and other democracies to work together with the alliance to defend the international order.
``NATO needs to make sure we have friends,'' he said, citing escalating Chinese attempts to coerce neighbors and threaten Taiwan. ``It is important to work more closely with our partners in the Indo-Pacific.''
China's Foreign Ministry responded by accusing NATO of exceeding its mandate and having ``played up China's threats.''
``China is always a force for regional and global peace and stability,'' ministry spokesperson Mao Ning said at a regular briefing.
``I would like to stress that the Asia-Pacific is not a battlefield for the geopolitical contest and does not welcome the Cold War mentality and bloc confrontation,'' Mao said.
It wasn't clear what prompted the Chinese action in Taiwan, although it came just ahead of a visit to Beijing by U.S. Secretary of State Antony Blinken, who would become the highest-ranking official to visit China since President Joe Biden's election in 2020.
Beijing frequently seeks to flag Taiwan as the most serious issue in U.S.-China relations ahead of top-level discussions, leading then to discussions of other economic, trade, and political issues where there is more room for meaningful exchanges.
China has sent warships, bombers, fighter jets, and support aircraft into airspace near Taiwan on a near-daily basis, hoping to wear down the island's limited defense resources and undercut support for pro-independence President Tsai Ing-wen.
Chinese fighter jets have also confronted military aircraft from the U.S. and allied nations over international airspace in the South China and East China seas, in what Beijing has described as dangerous and threatening maneuvers.
A string of visits in recent months by foreign politicians to Taiwan, including by then-U.S. House Speaker Nancy Pelosi and numerous politicians from the European Union, spurred displays of military might from both sides.
In response to Pelosi's visit in August, China staged war games surrounding the island and fired missiles over it into the Pacific Ocean.
China has repeatedly threatened retaliation against countries seeking closer ties with Taiwan, but its attempts at intimidation have sparked a backlash in popular sentiment in Europe, Japan, the U.S., and other nations.
Taiwan is set to hold presidential elections next year, in contrast to China's system of total control by President and party General Secretary Xi Jinping, who has removed term limits to effectively make him a leader for life. China's efforts to reach out to Taiwan's pro-unification Nationalist Party have largely backfired.
Although the Nationalists performed well in local elections last year, the party's pro-Beijing policies have failed to find resonance among voters on a national level.
Taiwan has responded to China's threats by ordering more defensive weaponry from the U.S., leveraging its democracy and high-tech economy to strengthen foreign relations and revitalizing its domestic arms industry.
Compulsory military service for men is being extended from four months to one year and public opinion surveys show high levels of support for increased defense spending to counter China's threats.
In an interview, last month, Taiwan's envoy to the U.S. said the island has learned important lessons from Russia's war in Ukraine that would help it deter any attack by China or defend itself if invaded.
Taiwan's de facto ambassador in Washington, Bi-khim Hsiao, said there is a new emphasis on preparing military reservists and civilians for the kind of all-of-society fight that Ukrainians are waging against Russia.
``Everything we're doing now is to prevent the pain and suffering of the tragedy of Ukraine from being repeated in our scenario in Taiwan,'' Hsiao told The Associated Press. ``So ultimately, we seek to deter the use of military force. But in a worst-case scenario, we understand that we have to be better prepared.''