The US has imposed sanctions on senior officials in the International Criminal Court (ICC), including chief prosecutor Fatou Bensouda.
Secretary of State Mike Pompeo accused the court of “illegitimate attempts to subject Americans to its jurisdiction”.
The Hague-based ICC is currently investigating whether US forces committed war crimes in Afghanistan.
The US has criticised the court since its foundation and is one of a dozen states which have not signed up.
President Donald Trump issued an executive order in June allowing the US to block the assets of ICC employees. He has repeatedly attacked the body and questioned its independence.
Addressing reporters on Wednesday, Mr Pompeo said these sanctions were the “next step”, following on from that order.
Dismissing the ICC as a “thoroughly broken and corrupted institution”, he said sanctions would apply to Ms Bensouda and Phakiso Mochochoko, the head of the Jurisdiction, Complementarity and Cooperation Division, for helping her.
“Individuals and entities that continue to materially support those individuals risk exposure to sanctions as well,” he said.
The US state department has also restricted the issuance of visas for ICC staff involved in “efforts to investigate US personnel”.