Chinese and Taiwanese warships played high seas "cat and mouse" on Sunday ahead of the scheduled end of four days of unprecedented Chinese military exercises launched in reaction to a visit to Taiwan by US House Speaker Nancy Pelosi.
Pelosi's visit last week infuriated China, which regards the self-ruled island as its territory and which responded with test launches of ballistic missiles over the island's capital for the first time and the cutting of some areas of dialogue with Washington.
About 10 warships each from China and Taiwan sailed at close quarters in the Taiwan Strait, with some Chinese vessels crossing the median line, an unofficial buffer separating the two sides, according to a person with knowledge of the matter.
The island's defence ministry said multiple Chinese military ships, aircraft, and drones were simulating attacks on the island and its navy. It said it had sent aircraft and ships to react "appropriately".
In a statement later on Sunday, the ministry said it had detected 14 Chinese warships and 66 Chinese aircraft in and around the Taiwan Strait.
It was not immediately clear if China had ended the drills on Sunday, as previously announced. But a late-evening commentator on Chinese state television said the Chinese military would now conduct "regular" drills on the Taiwan side of the line, saying the "historic task" of China's "reunification" could be realised.
As Chinese forces "pressed" the line, as they did on Saturday, the Taiwan side stayed close to monitor and, where possible, deny the Chinese the ability to cross, said the person with knowledge of the situation who declined to be identified.
"The two sides are showing restraint," the person said, describing the manoeuvres as high seas "cat and mouse".
Taiwan said its shore-based anti-ship missiles and its Patriot surface-to-air-missiles were on stand-by.
The defence ministry said its F-16 jet fighters were flying with advanced anti-aircraft missiles. It issued photographs of Harpoon anti-ship weapons being loaded on another.
Speaking during a visit to Bangladesh, Chinese Foreign Minister Wang Yi said his country's actions were "legitimate, reasonable, in accordance with the law," and aimed at protecting China's "sacred sovereignty".
"It must be borne in mind that Taiwan is not a part of the US - it is China's territory," Wang's ministry cited him as saying.
The Chinese exercises, centred on six locations around the island, began on Thursday and were scheduled to last until midday on Sunday, the official Xinhua News Agency reported last week.
There was no announcement from China on Sunday on whether the exercises had ended and Taiwan said it was unable to verify whether China had stopped them as scheduled.
Nevertheless, Taiwan's transport ministry it was gradually lifting restrictions on flights through its airspace, saying notifications for the drills were no longer in effect.
But it added that Taiwan would continue to direct flights and ships away from one of the drill zones off its east coast until Monday morning.
China's military has said the sea and air joint exercises, north, southwest and east of Taiwan, had a focus on land-strike and sea-assault capabilities.
The US called the exercises a significant escalation in China's efforts to change the status quo.
"They are provocative, irresponsible and raise the risk of miscalculation," a White House spokesperson said. "They are also at odds with our long-standing goal of maintaining peace and stability across the Taiwan Strait."
China says its relations with Taiwan are an internal matter and it reserves the right to bring the island under its control, by force if necessary. Taiwan rejects China's claim, saying only Taiwan's people can decide their future.
China has warned the US not to "act rashly" and create a greater crisis and the state-run Xinhua News Agency said in a commentary that Pelosi had staged a "political stunt" out of self-interest.
"Insisting on going to the island, she apparently does not care about harming China-US ties, or putting peace across the Taiwan Strait on the line," it said.
Pelosi, a long-time China critic and a political ally of President Joe Biden, arrived in Taiwan late on Tuesday on the highest-level visit to the island by an American official in decades, despite Chinese warnings. She said her visit showed unwavering US commitment to supporting Taiwan's democracy.
Speaking at a news conference in Japan on Friday, Pelosi said her trip to Asia was "not about changing the status quo in Taiwan or the region".
Taiwan's foreign ministry condemned China's "aggressive and provocative" exercises and urged it "to immediately stop such tension-escalating behaviours that have endangered the common good of the region and the world".
As part of its response to Pelosi's visit, China has halted dialogue with the United States in a series of areas including contacts between theatre-level military commanders and on climate change.
Chiang Kai-shek's defeated Republic of China government fled to Taiwan in 1949 after losing a civil war to Mao Zedong's communists, who proclaimed the People's Republic of China in Beijing.