A deputy police commissioner, Edwina Lau, said on Tuesday that an attempt by the US government to use "so-called sanctions" to strike a blow to the force's work on national security would be "futile".
Lau, who is one of four Hong Kong and mainland officials hit by a new round of sanctions from Washington, said she is not at all scared by the move, and is proud and honoured to be in charge of the police's national security unit.
In a statement issued by the force's public relations department, Lau said she is determined to keep carrying out her work on national security.
Another of the latest officials to be sanctioned, senior superintendent Steve Li, said maintaining national security is the natural responsibility of police officers in any place.
He said he is determined to enforce the law and is "unshaken" by the sanctions.
Li said defending Hong Kong and serving in the force are an honour for him and he will continue to carry out his duties.
A deputy director of the Hong Kong and Macau Affairs Office, Deng Zhonghua, and a deputy director of the Office for Safeguarding National Security, Li Jiangzhou, are the other two officials being slapped with sanctions.
In August, Chief Executive Carrie Lam, Justice Secretary Teresa Cheng, Security Secretary John Lee, Police Commissioner Chris Tang and seven other Hong Kong and mainland officials were also hit with US sanctions for their roles in implementing Hong Kong's national security law.