A blitz against the ICC by Pompeo and other cabinet officials Thursday came three months after the court announced it had approved an investigation into members of the U.S. military and CIA for possible war crimes in Afghanistan.
The ICC originally rejected its prosecutor's request to investigate last year, but that decision was successfully appealed in March.
"Just for a time it looked like the ICC might do the right thing and kill the investigation," Pompeo said.
The U.S. never consented to the ICC's founding document, the Rome Statute, and so is not subject to its judgement, according to Pompeo.
"And even if a prosecution were to proceed, it would make a mockery of due process," Pompeo said. "There's no requirement for unanimity for a conviction; the prosecution can rely on hearsay to obtain a conviction; there's no real guarantee of a speedy trial; instead of facing a jury of one's peers, it's a panel of judges who aren't subject to any American accountability."
The secretary went on to call the ICC "grossly ineffective and corrupt" and a "kangaroo court," warning U.S. allies: "Your people could be next."
A statement from the White House Thursday morning suggested the ICC's investigation is a politically motivated ploy involving antagonistic countries to harm the U.S.
Attorney General William Barr named Russia during Thursday's press conference with Pompeo.
"This institution has become in practice a little more than a political tool employed by unaccountable international elites," Barr said. "These people wield this tool to manipulate and undercut the foreign policies of a democratically accountable sovereign nation, and other nations, including the United States ... Worse yet, we are concerned that foreign powers like Russia are also manipulating the ICC in pursuit of their own agenda."
Barr claimed his agency has evidence of ICC corruption, but did not give details.
"The U.S. government has reason to doubt the honesty of the ICC: The Department of Justice has received substantial credible information that raises serious concerns about a long history of financial corruption and malfeasance at the highest levels of the Office of the prosecutor," Barr said.
Secretary of Defense Mark Esper, also at the press conference with Pompeo, pledged that no U.S. personnel will ever stand before the Hague-based court.
"Rest assured that the men and women of the United States armed forces will never appear before the ICC, and nor will they ever be subjected to the judgments of unaccountable international bodies."
The George W. Bush administration withdrew the U.S. from the ICC treaty before it went into effect in 2002.
Defense Secretary Donald Rumsfeld said in a statement at the time that "the United States will regard as illegitimate any attempt by the court or state parties to the treaty to assert the ICC's jurisdiction over American citizens."
Rob Berschinski, senior vice president for policy at Human Rights First, said Trump's threat of asset freezes and visa restrictions against ICC officials is counterproductive.
“Among other things, it appears to put foreign persons within human rights organizations at risk of sanctions, if those persons have conducted research and reporting on alleged criminal activity by U.S. or allied forces that is used to 'assist' an ICC investigation," Berschinski said. "Furthermore, it appears to indicate that the U.S. Government could sanction ICC staff and their families if they were to investigate crimes in countries allied with the United States."
National Security Advisor Robert O’Brien joined his fellow Trump cabinet members in condemning the ICC Thursday, saying U.S. service members should only be accountable to U.S. laws and institutions.
"I was a JAG officer in the Army and I can tell you the United States government military justice systems are far more effective at holding Americans accountable than the ICC ever has been or ever will be, and we will never allow our American soldiers, sailors, airmen and Marines to fall into the jurisdiction of that purported court," O'Brien said.
ABC News' Conor Finnegan contributed to this report.