China warned Tuesday it would take “resolute and forceful measures” if US House of Representatives Speaker Nancy Pelosi visits Taiwan, in what would be the highest-level delegation from the United States to the self-governing island in 25 years.

Pelosi, who is second in line of succession to the US presidency, has reportedly outlined plans to take a delegation to Taipei in August, according to the Financial Times, citing people familiar with the matter. Pelosi's office declined to comment on her travel plans.

August 1 is the anniversary of the founding of China's People's Liberation Army.

On Tuesday, China's Foreign Ministry lashed out at the potential visit, saying it would “have a severe negative impact on the political foundation of China-US relations, and send a gravely wrong signal to 'Taiwan independence' separatist forces.”

“If the US insists on going down the wrong path, China will definitely take resolute and forceful measures to firmly defend its national sovereignty and territorial integrity,” ministry spokesperson Zhao Lijian told a news conference. “The United States must be fully responsible for all the consequences caused by this.”

Beijing's ruling Communist Party has long claimed Taiwan as part of its territory and has repeatedly vowed to “reunify” the island of 24 million people with the Chinese mainland -- by force if necessary -- despite having never governed it.

Pelosi had previously planned to lead a US congressional delegation to Taiwan in April, but the trip was postponed after she tested positive for Covid-19. At the time, China had strongly opposed the trip and issued similar warnings.

Her visit would be the first by a sitting House Speaker since Republican Newt Gingrich traveled to Taiwan in 1997.

Taiwan has seen a flurry of visits by American delegations in recent years, especially after the Taiwan Travel Act was signed into law by then US President Donald Trump in March 2018. Since then, US officials and lawmakers have embarked on more than 20 trips to the democratically controlled island, according to a CNN tally.

China, meanwhile, has sent record numbers of war planes near Taiwan, as cross-strait tensions soared to their highest in recent decades.

Asked if he was worried that Pelosi's Taiwan trip could send the wrong message for the US-China relationship, House Majority Leader Steny Hoyer told CNN: “I think the President's position is pretty clear on our relationship with Taiwan. So the answer to that question is I don't think it will be a surprise to the Chinese or be a different message than we've been sending.”

Hoyer told CNN he would not join Pelosi on her trip to Taiwan, and did not know when she would be going. (CNN)

•PHOTO: US House of Representatives Speaker Nancy Pelosi speaks during a weekly news conference on Capitol Hill in Washington, DC on June 9.

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