The United States said it will deny visas to any member of the International Criminal Court involved in investigating the actions of US troops in Afghanistan or other countries.
Secretary of State Mike Pompeo said Washington was prepared to take further steps, including economic sanctions, if the war crimes court goes ahead with any probes of US or allied personnel.
"The ICC is attacking America's rule of law," Mr Pompeo told reporters on Friday. "It's not too late for the court to change course and we urge that it do so immediately."
The United States has never joined the ICC, whose chief prosecutor, Fatou Bensouda, asked judges in November 2017 for authorisation to open an investigation into alleged war crimes in Afghanistan. They included "acts of torture, cruel treatment, outrages upon personal dignity, rape and sexual violence against conflict-related detainees" in which US personnel may have been involved.
Mr Pompeo's announcement of visa restrictions was the first concrete action taken by the US against the ICC since the White House threatened reprisals against the Hague-based body in September of last year.
"I'm announcing a policy of US visa restrictions on those individuals directly responsible for any ICC investigation of US personnel," the secretary of state said.
This would include anyone who takes, or has taken, action to request or further an investigation.
"If you're responsible for the proposed ICC investigation of US personnel in connection with the situation in Afghanistan you should not assume that you still have, or will get, a visa or that you will permitted to enter the United States," Mr Pompeo said.
The secretary of state said visas could also be used to "deter ICC efforts to pursue allied personnel, including Israelis, without allies' consent".
He said implementation of the policy had already begun but he did not provide any details, citing confidentiality surrounding visa applications.
"These visa restrictions will not be the end of our efforts. We're prepared to take additional steps, including economic sanctions, if the ICC does not change its course."
The US was among the signatories to the Rome Statute under which the ICC was established in 2002, but its membership was never ratified by the Senate.
The secretary of state said the US had declined to join the ICC "because of its broad unaccountable prosecutorial powers" and its threat to American national sovereignty.
"We are determined to protect American and allied civilian personnel from living in fear of unjust prosecution for actions taken to defend our great nation," he said.
"We feared that the court could eventually pursue politically motivated prosecutions of Americans," he said, "and our fears were warranted".
Mr Pompeo said procedures were already in place to deal with members of the US armed forces who engage in misconduct.
"When US service members fail to adhere to our strict code of military conduct they are reprimanded, court-martialed and sentenced, if that's what's deserved," he said.
"The US government, where possible, takes legal action against those responsible for international crimes," he added, noting that it has supported prosecution of war crimes in Rwanda, the former Yugoslavia and elsewhere.
The ICC and human rights groups reacted swiftly to Mr Pompeo's remarks.
"The ICC, as a court of law, will continue to do its independent work, undeterred, in accordance with its mandate and the overarching principle of the rule of law," the ICC said.
Richard Dicker, international justice director at Human Rights Watch, said the US move "is a naked attempt to bully judges and impede justice for victims in Afghanistan" and "blatant contempt for the rule of law".
James Goldston, executive director of the Open Society Justice Initiative, said Mr Pompeo's remarks reflected the administration's view that international law matters "only when it is aligned with US national interests".
"Attacking international judicial actors for doing their jobs undermines global efforts to hold to account those most responsible for atrocity crimes such as torture and mass murder," he said.
The "America First" administration of President Donald Trump has been a particularly virulent opponent of the ICC.
John Bolton harshly condemned the court in one of his first speeches after becoming Mr Trump's national security adviser in September.
"We will not co-operate with the ICC," Mr Bolton said. "And we certainly will not join the ICC. We will let the ICC die on its own."