The heads of the FBI and MI5 have joined forces to warn that China poses the biggest long-term threat to the security of the US, the UK and their allies.
FBI director Christopher Wray reaffirmed longstanding concerns in denouncing economic espionage and hacking operations by China as well as the Chinese government's efforts to stifle dissent abroad.
But his speech was notable because it took place at MI5's London headquarters and alongside the British domestic intelligence agency's director-general, Ken McCallum, in an intended show of Western solidarity.
"We consistently see that it's the Chinese government that poses the biggest long-term threat to our economic and national security, and by 'our,' I mean both of our nations, along with our allies in Europe and elsewhere," Mr Wray said.
Mr McCallum said the Chinese government and its "covert pressure across the globe" posed "the most game-changing challenge we face".
"This might feel abstract. But it's real and it's pressing," he said.
"We need to talk about it. We need to act."
Separately, Australia's Foreign Minister Penny Wong called on China to show "restraint" in its dealings with smaller countries in the region, during a major policy address in Singapore.
A spokesman for the Chinese embassy in Washington, Liu Pengyu, rejected the allegations from MI5 and the FBI, saying in an emailed statement to The Associated Press that China "firmly opposes and combats all forms of cyber attacks" and calling the accusations groundless.
"We will never encourage, support or condone cyber attacks," the statement said.
In a nod to current tensions between China and Taiwan, Mr Wray also said during his speech that any forcible takeover of Taipei by Beijing "would represent one of the most horrific business disruptions the world has ever seen".
Last week, the US government's director of national intelligence, Avril Haines, said at an event in Washington that there were no indications Chinese President Xi Jinping was poised to take Taiwan by military force.
But she did say Mr Xi appeared to be "pursuing the potential" for such an action as part of a broader Chinese government goal of reunification with Taiwan.
After the appearance with his British counterpart, Mr Wray said that he would leave to others the question of whether an invasion of Taiwan was more or less likely after Russia's invasion of neighbouring Ukraine.
But, he said: "I don't have any reason to think their interest in Taiwan has abated in any fashion."
He added that he hoped China had learned what happens "when you overplay your hand," as he said the Russians had done in Ukraine.
The FBI director said there were signs the Chinese, perhaps drawing lessons from Russia's experience since the war, had been looking for ways to "insulate their economy" against potential sanctions.
"In our world, we call that behaviour a clue," he said.
He also urged caution from Western companies looking to do business in or with China, saying Western investments could collapse in the event of an invasion of Taiwan.
"Just as in Russia, Western investments built over years could become hostages, capital stranded [and] supply chains and relationships disrupted," he said.
President Joe Biden said in May that the US would respond militarily if China invaded Taiwan, offering one of the most forceful White House statements in support of Taiwan's self-governing in decades.
The White House later tried to soften the impact of the statement, saying Mr Biden was not outlining a change in US policy toward Taiwan, a self-governing island that China views as a breakaway province that should be reunified with the mainland.
The Chinese embassy spokesman said the Taiwan issue was "purely China's internal affair" and said when it came to questions of China's territory and sovereignty, the country had "no room for compromise or concession."
"We will strive for the prospect of peaceful reunification with utmost sincerity and efforts," the statement said, though it noted that China will "reserve the option of taking all necessary measures in response to the interference of foreign forces."
ABC/AP
