The United States government has expressed concern about recent statements by a senior Chinese military official suggesting that mainland forces could be deployed in Hong Kong to quell dissent on the city’s streets. “We note with concern the Chinese government’s statements,” a state department spokeswoman told the South China Morning Post on Thursday. “We urge Beijing to adhere to its commitments in the Sino-British Joint Declaration and Basic Law to allow Hong Kong to exercise a high degree of autonomy,” she said, referring to the binding documents that stipulate the city’s administrative autonomy under the “one country, two systems” framework. The comments came a day after Chinese defence ministry spokesman Wu Qian said that protesters’ recent actions were challenging Beijing’s baseline and made clear that the People’s Liberation Army (PLA) was legally permitted to maintain law and order under the city’s Garrison Law. “Some behaviour of the radical protesters is challenging the authority of the central government and the bottom line of one country, two systems,” said Wu, who singled out protesters’ recent vandalism of Beijing’s liaison office in Hong Kong. Though analysts say the prospect of military intervention is extremely unlikely due to the political cost , Wu’s remarks fuelled concerns among Hongkongers that the PLA’s hitherto dormant presence in the city could change, particularly given memories of the Chinese military’s bloody crackdown on protesters in Beijing 30 years ago. Concern crested in Washington, too, with lawmakers on Wednesday calling for a swift rebuke from the US government. “The Trump administration should strongly and publicly condemn any threats to Hong Kong citizens and US residents of Hong Kong,” senator Marco Rubio and representative James McGovern said in a statement. “We also ask the Hong Kong government to condemn the Chinese government’s threats as unwelcome interference in Hong Kong’s affairs.” Protests against Beijing's influence over Hong Kong have raged through the city for nearly two months, prompted by a proposed amendment to Hong Kong law that would have allowed the extradition of suspects to mainland China. Mainland China sentiment on protests ‘may spur tougher line on Hong Kong’ The state department on Thursday expressed support for protesters’ “broad and legitimate concerns about the erosion of Hong Kong’s autonomy”, which it said threatened the city’s place in international affairs. Beijing has shot back against any critique from foreign governments over the protests, accusing – without evidence – US government officials on Tuesday of being behind the ongoing unrest. The state department said it “categorically reject[ed] the false charge of foreign forces as the black hand behind the protests”, referring to an allegory often employed by Beijing to refer to external interference. Protesters – who have faced riot-control-level tactics from Hong Kong police, including rubber pellets, tear gas and batons – came up against a new form of resistance over the weekend when gangs of white-clad men apparently belonging to organised crime groups set upon demonstrators with metal poles and bats. The indiscriminate violence, which took place in the border town of Yuen Long north of the city, left 45 people injured, including journalists and other passers-by. The US state department said on Thursday that reports of “organised violence by criminal gangs against private citizens, and attacks on journalists trying to do their jobs, are particularly disturbing.” “We urge all sides to exercise restraint and refrain from violence,” its spokeswoman said. Accusations of complicity in Sunday’s attacks by Hong Kong authorities have swirled since it was revealed that it took about 40 minutes for police to arrive at the scene, charges the city’s leadership has denied. Allegations of collusion were also fuelled following the release of footage showing a pro-establishment lawmaker shaking hands with and thanking a group of men in white T-shirts on Sunday evening. The lawmaker, Junius Ho Kwan-yiu, has continued to grab headlines since then with his defence of the mob’s right to defend their “home and people”, an apparent death threat made against a pro-democracy lawmaker via Facebook, and an interview with Chinese state media on Thursday in which he said the PLA could intervene to “stabilise the political situation”.