TAIPEI/BEIJING - US House of Representatives Speaker Nancy Pelosi arrived in Taipei on Tuesday night (Aug 2) - the highest-ranking US politician to visit in 25 years - angering China into announcing "targeted military actions" in response to her visit.

“The Chinese People’s Liberation Army (PLA) is on high alert and will launch a series of targeted military operations to counter this, resolutely defend national sovereignty and territorial integrity, and resolutely thwart external interference and ‘Taiwan independence’ separatist attempts,” army spokesman Wu Qian said in a statement.

Military drills including “long-range live firing in the Taiwan Strait” and “regular-guided fire testing in the eastern waters” off Taiwan were being planned from Tuesday evening, the PLA's Eastern Theatre Command said. 

The Xinhua News Agency reported separately that China will hold military drills from Aug 4 to 7 in six areas around Taiwan. 

Ships and aircraft were warned against trespassing in those areas – some of which overlap with the island’s territorial waters.

In a statement released shortly after her touchdown, Mrs Pelosi said the visit honours the United States' unwavering commitment to supporting Taiwan’s democracy, and "in no way contradicts longstanding US policy".

Beijing, which regards Taiwan as a renegade province that will be retaken by force if necessary, views Mrs Pelosi's visit as sending an encouraging signal to the pro-independence camp on the self-ruling island. It has not ruled out a military response.

In a stinging statement on Tuesday night, the Chinese Foreign Ministry accused Washington of attempting to use Taiwan to contain China.

"It constantly distorts, obscures and hollows out the one-China principle, steps up its official exchanges with Taiwan, and emboldens 'Taiwan independence' separatist activities," it said, warning that "those who play with fire will perish by it".

Beijing, it said, will take all necessary measures to resolutely safeguard its sovereignty and territorial integrity in response to the US Speaker’s visit.

"All the consequences arising therefrom must be borne by the US side and the 'Taiwan independence' separatist forces," it added.

The US Navy reportedly deployed four warships in waters east of Taiwan in what it called "routine" deployments.

Meanwhile, Taiwan's presidential office claimed it was hit by a barrage of cyber attacks in the evening.

Mrs Pelosi arrived at Taipei's Songshan Airport on Tuesday night, after her US Air Force SPAR19 flight left the Malaysian capital Kuala Lumpur and took a longer route, flying south-east towards Borneo before circling up north towards the direction of Taiwan, according to flight tracking website Flightradar24.

It appeared to be avoiding flying over the South China Sea, where the Chinese army has held various exercises, including live fire drills, since last week.

Ordinarily, a flight between Kuala Lumpur and Taipei takes about five hours. The detour added about two more hours.

Mrs Pelosi’s visit, which was previously unannounced, is part of her tour of the Indo-Pacific, which started in Singapore on Monday and then to Malaysia on Tuesday.

Media reports said Mrs Pelosi would visit Taiwan's Legislative Yuan, or the Parliament, and meet President Tsai Ing-wen on Wednesday, which was not officially on her agenda.

"Our discussions with Taiwan leadership will focus on reaffirming our support for our partner and on promoting our shared interests, including advancing a free and open Indo-Pacific region. America’s solidarity with the 23 million people of Taiwan is more important today than ever, as the world faces a choice between autocracy and democracy," Mrs Pelosi said in her statement.

She added that her visit is one of several congressional delegations to Taiwan and that the US "continues to oppose unilateral efforts to change the status quo".

The US delegation was welcomed by Taiwan’s Foreign Minister Joseph Wu and American Institute in Taiwan Director Sandra Oudkirk.

Taiwan’s Foreign Affairs Ministry said the visit “emphasises the high level of support Taiwan-US relations is receiving from the US House of Representatives, as well as the two sides’ extensive collaborations across various fields”.

Its Defence Ministry said on Tuesday morning that it was monitoring China’s military activities and will dispatch appropriate forces if there are any “enemy threats”. 

Taiwan’s presidential office claimed on Tuesday that it was hit by a barrage of cyber attacks in the evening.