The US has imposed sanctions on a dozen Russian and Chinese companies and individuals it accuses of helping North Korea’s nuclear weapons programme.
Earlier this month, members of the UN Security Council, including Russia and China, voted for further sanctions against Pyongyang.
The US Treasury said the move would “increase pressure” on North Korea.
China responded swiftly, calling on the US to “immediately correct its mistake” of punishing its firms.
The US Office of Foreign Assets Control designated 10 companies and six individuals in its sanctions.
“[The] Treasury will continue to increase pressure on North Korea by targeting those who support the advancement of nuclear and ballistic missile programmes, and isolating them from the American financial system,” said Treasury Secretary Steven Mnuchin.
The action means American individuals and companies are no longer permitted to do business with these firms.
A series of missile tests by Pyongyang has increased tensions between North Korea and the US, with both sides engaged in a heated exchange of threats.
~ Albert Einstein