The US on Saturday called a decision by Beijing to impose restrictions on all American diplomats on Chinese soil an "escalation," the latest rebuke in an ongoing tit-for-tat dispute over foreign missions.
Relations between the world's top two economies have deteriorated in recent months, with both sides locked in fierce recriminations over trade disputes, human rights and the origins of the coronavirus pandemic.
On Friday China announced "reciprocal restrictions" against US diplomats, days after Washington announced new restrictions on staff working for Beijing's foreign missions.
Beijing said that the unspecified countermeasures will apply to all US embassy and consulate staff, including the consulate-general in Hong Kong and its personnel, and called the move a "legitimate and necessary response."
But the US said Saturday that the Chinese measures went further than anything it had done.
A State Department spokesperson who spoke on condition of anonymity said Beijing's move was an "escalation," citing the targeting of its representative in Hong Kong and restrictions on Chinese citizens meeting with Americans in the form of a "new meeting pre-notification requirement."
"These notification requirements now include American citizens with no affiliation to the US government. We have no such requirement for PRC citizens," the spokesperson said, using the acronym for the People's Republic of China.
The dispute over foreign missions flared up in July when Washington ordered the closure of the Chinese consulate in Houston, prompting Beijing to shutter the American presence in Chengdu.
The battle over diplomatic outposts is only one front in an escalating confrontation between the US and China.
Washington has imposed sanctions on officials accused of helping orchestrate China's mass internment of Uighurs and other mostly Muslim minorities in the country's Xinjiang region, a program that has prompted a global human rights outcry.
Last month it blacklisted officials it accused of suppressing "freedom and democratic processes" in Hong Kong, after the imposition of a national security law aimed at quelling civil unrest in the financial hub.
The move prompted China to issue its own sanctions against several prominent Americans.
President Donald Trump has also provoked a furious reaction from Chinese officials by blaming Beijing for the global spread of the coronavirus
And Washington has additionally accused Chinese tech firms and platforms — from Huawei to TikTok — of working in the interests of the Chinese Communist Party.
Beijing denied on Friday it was attempting to meddle in the upcoming US presidential election after tech giant Microsoft said it thwarted cyberattacks from overseas groups — including from China.