The Chinese flag flies outside of the Chinese consulate in Houston after the US State Department ordered China to close the consulate in Houston, Texas, July 22, 2020. (Photo by MARK FELIX/AFP /AFP via Getty Images)

China warned on Thursday it will be forced to respond after the United States ordered the shutdown of its Houston consulate, a move the Chinese Foreign Ministry said had “severely harmed” relations.

Washington gave China 72 hours to close the consulate “to protect American intellectual property and Americans’ private information”, marking a dramatic escalation of tension between the world’s two biggest economies.

Republican Senator Marco Rubio, acting chairman of the Senate Intelligence Committee, described the Houston consulate on Twitter as the “central node of the Communist Party’s vast network of spies & influence operations in the United States”.

Chinese Foreign Ministry spokesman Wang Wenbin, speaking at a daily media briefing, described the U.S. allegations as “malicious slander”.

“In response to the U.S.’s unreasonable actions, China must make a necessary response and safeguard its legitimate rights,” he said, declining to specify any measures.

“This is tearing down the friendly bridge between the people of China and the U.S.,” he added.

The South China Morning Post reported that China may close the U.S. consulate in the southwestern city of Chengdu, while a source told Reuters on Wednesday that China was considering shutting the U.S. consulate in Wuhan, where the United States withdrew staff at the start of the coronavirus outbreak.

Hu Xijin, editor the Global Times, a tabloid published by the ruling Communist Party’s official People’s Daily, wrote that shutting the Wuhan consulate would be insufficiently disruptive.

Hu said the United States had a large consulate in Hong Kong and it was “too obvious that the consulate is an intelligence centre”.

“Even if China doesn’t close it, it could instead cut its staff to one or two hundred. This will make Washington suffer much pain,” he wrote.

The other U.S. consulates in China are in Guangzhou, Shanghai and Shenyang.

U.S.-China ties have deteriorated sharply this year over issues ranging from the coronavirus and telecoms-gear maker Huawei to China‘s territorial claims in the South China Sea and its clampdown on Hong Kong.

Separately, the Federal Bureau of Investigation has alleged in U.S. court filings that a Chinese researcher accused of visa fraud and concealing ties to the military was now holed up in China‘s consulate in San Francisco.

Other Chinese researchers at U.S. universities have also been arrested for visa fraud, according to U.S. court filings.

Wang said China would safeguard its citizens.

“For some time, the U.S. has held ideological bias to continuously surveil, harass and even arbitrarily detain Chinese students and scholars in the U.S.,” he said.

“We urge the U.S. to stop using any excuse to restrict, harass or oppress Chinese students and researchers in the U.S.”

Chinese state media editorials criticised the U.S. order to shut the Houston consulate as an attempt to blame Beijing for U.S. failures ahead of the November presidential election.

Polls show President Donald Trump trailing his challenger, former Vice President Joe Biden, ahead of the Nov. 3 election as the worsening coronavirus crisis exacts a deep toll on the U.S. economy.

The official China Daily described the closure of the consulate as “a new gambit in the U.S. administration’s bid to paint China as a malevolent actor on the world stage, and thus make it an outlaw to the international community”.

“The move shows that lagging behind his presidential election opponent in the polls … the U.S. leader is going all out in his attempts to portray China as an agent of evil,” it said.