Beijing's biggest maritime drills in years involve about 60 warships and 30 coast guard vessels deployed from near the southern islands of Japan to the South China Sea, a senior national security official told AFP on the condition of anonymity.
China has also ramped up military aircraft activity closer to Taiwan, with 100 sorties detected over the past two days, figures from the island's defence ministry show.
There has been no public announcement by Beijing's army or Chinese state media about increased military activity in the East China Sea, Taiwan Strait, South China Sea or Western Pacific Ocean.
But a recent Pacific tour by Taiwanese President Lai Ching-te that included two stops in US territory drew fury from Beijing, which claims the democratic island as part of China's territory.
The security official said Wednesday that China's plans for the massive maritime operation began in October and were aimed at demonstrating that Beijing could choke off Taiwan and also to "draw a red line" ahead of the next US administration.
"China uses President Lai's overseas visit as a pretext, with Taiwan only serving as an excuse," the official said.
"The real objective appears to be asserting control within the first island chain and establishing strategic deterrence ahead of the US presidential transition."
Taiwan's foreign ministry said Wednesday that China's increased military activity around the island, including its huge maritime drills and frequent aircraft deployments, was evidence that Beijing was a "troublemaker".
US Defense Secretary Lloyd Austin said the United States was monitoring China's "latest activity" and would ensure "nobody does anything to change the status quo in the (Taiwan) Strait".
"Again, our policy hasn't changed. We'll continue to do what we can to help Taiwan acquire the means to defend itself," Austin told reporters at a US base in Japan on Wednesday.
Simulating attacks, blockade
During the drills, Chinese warships have simulated attacking foreign ships while the coast guard has practised intercepting commercial vessels as well as disrupting and blockading sea routes, the official said.
China also held "joint operations with Russia" over several days in November, the official said.
Recent bad weather had "posed challenges for smaller vessels" involved in the drills, they said.
Taiwan lives under the constant threat of invasion by China, which has not ruled out using force to bring the island under its control.
To press its claim over self-ruled Taiwan, China has ramped up the deployment of fighter jets and warships around the island in recent years.
China also opposes any international recognition of Taiwan and especially bristles at official contact between Taipei and Washington.
In addition to his two recent stopovers on American soil, Lai spoke with Republican House Speaker Mike Johnson, which drew a barrage of criticism from China.
Beijing's foreign ministry spokeswoman said Tuesday that China would "resolutely defend" its sovereignty.
'Significantly larger'
The security official said the sea drills were "significantly larger" than Beijing's maritime response to then-US House speaker Nancy Pelosi's visit to Taipei in 2022, which was China's largest-ever war games around Taiwan.
China has held four major military exercises in just over two years, including the drills in response to Pelosi's visit and two since Lai took office in May.
Beijing usually announces its military exercises, but the official said one of the reasons it may have decided to stay silent was to avoid overshadowing China's annual Central Economic Work Conference.
China's leadership will gather Wednesday for a closed-door meeting to hammer out plans to boost the economy next year, reports said.
The Taiwan defence ministry's daily tally of Chinese aircraft detected around the island was 53 on Wednesday and 47 on Tuesday.
Wednesday's figure was the highest number of aircraft detected in a single day since a record 153 were reported on October 15 after China staged large-scale military drills in response to Lai's National Day speech days earlier.
