The US Treasury has imposed sanctions on Hong Kong chief executive Carrie Lam, and 10 other top officials from Hong Kong and mainland China, APA reports citing BBC.
The sanctions were used to target those undermining Hong Kong's autonomy, said Treasury Secretary Steven Mnuchin.
"The United States stands with the people of Hong Kong," Mr Mnuchin added.
The move comes weeks after China imposed a controversial national security law on Hong Kong, which critics say threatened its freedoms.
US-China tensions continue to escalate - only a few hours ago, the Trump administration moved to ban US transactions with the Chinese owners of the WeChat and TikTok apps..
Among those sanctioned are Hong Kong's police commissioner and several political secretaries.