Judges in the Appeals Chamber of the International Criminal Court on Thursday authorized Chief Prosecutor Fatou Bensouda to open an investigation into alleged U.S. war crimes in Afghanistan. This is a big milestone in international criminal justice — for the first time in history, U.S. leaders, armed forces and intelligence personnel may face a trial in an international court for crimes perpetrated in the context of the nation’s wars abroad.

In April, the Pre-Trial Chamber rejected Bensouda’s first request for an investigation. On Thursday, Secretary of State Mike Pompeo condemned the Appeals Chamber’s overturning of the decision, calling the ICC “an unaccountable political institution masquerading as a legal body.”

What are the alleged abuses? How does the ICC have jurisdiction over the United States? What will ordinary U.S. citizens make of an ICC investigation? My research explains how U.S. citizens are more supportive of the ICC than the Trump administration’s rhetoric suggests.

The ICC prosecutor examined evidence of U.S. torture and abuse

In 2006, the ICC’s Office of the Prosecutor (OTP) opened a preliminary examination into allegations of war crimes and crimes against humanity in the Afghan conflict since 2003 — the year Afghanistan became a member of the ICC.

The OTP examined allegations of abuses by both anti-government and pro-government forces, including the Taliban, the Afghan National Security Forces, the United States, armed forces and the CIA. The OTP says the information it gathered indicates, among other allegations, that U.S. interrogation techniques used in Afghanistan — involving “torture, cruel treatment, outrages upon personal dignity, and rape” — amount to war crimes.

Some ICC judges are worried about going after the U.S.

The United States is not a member of the ICC. However, the treaty that created the court, the Rome Statute, allows it to investigate citizens of nonmember states if the alleged crimes occurred on the territory of a member state. Once Afghanistan ratified the Rome Statute and joined the ICC in 2003, U.S. military and intelligence personnel in Afghanistan came under the court’s jurisdiction.

In November 2017 — after more than a decade of gathering evidence — the prosecutor requested authorization to open a full investigation, arguing there was “a reasonable basis to believe” U.S. military and intelligence personnel committed war crimes.

A year and a half later, in April 2019, the Pre-Trial Chamber unanimously rejected the request. The judges agreed the request was in the ICC’s jurisdiction and admissible before the ICC. However, they claimed the investigation would probably not be successful and, therefore, it would not serve the interests of justice to proceed.

The 2019 decision sparked controversy in the human rights community. Amnesty International and Human Rights Watch issued statements criticizing the court’s judges for capitulating to the Trump administration’s threats and, in the process, abandoning the victims of the alleged crimes.

The ICC will move ahead, despite the political risks

Bensouda swiftly appealed the decision. Her office coordinated a multifaceted response, drawing on submissions from victims’ legal representatives and amicus curiae briefs from human rights organizations.

On Thursday, the Appeals Chamber unanimously reversed the Pre-Trial Chamber’s decision, saying it had gone beyond its power by rejecting the prosecutor’s request. The Rome Statute requires only that the Pre-Trial Chamber determine whether “there is a reasonable basis to proceed with an investigation” and whether “the case appears to fall within the jurisdiction of the Court.”

Since these facts were not in dispute, there was no basis to reject the prosecutor’s request. Last week’s decision authorizes Bensouda and her team to proceed with the investigation. The Appeals Chamber also granted permission for the prosecutor and her team to investigate allegations of abuses that related to the conflict in Afghanistan but that occurred outside the territory strictly defined — notably in CIA “black site” detention facilities in Poland, Romania and Lithuania.

The U.S. is not happy

Pompeo stated in a news briefing Thursday that “we’re going to take all the appropriate actions to ensure that American citizens are not hauled before this political body to settle a political vendetta.” It is not yet clear what these actions will involve, but it seems unlikely the Trump administration will support the ICC investigation.

The Trump administration has long been hostile toward the ICC. President Trump’s statement from last April criticized the court’s “broad, unaccountable prosecutorial powers; [and] the threat it poses to American national sovereignty.” The administration has also shown its disapproval of the ICC by revoking U.S. visas for ICC personnel and threatening financial sanctions against ICC judges and prosecutors.

However, obstructing the ICC may be less popular with the U.S. public than one might think. My survey findings, detailed last April in the Monkey Cage, reveal the U.S. public is not hostile to the ICC.

In an article recently published in the International Studies Quarterly, I find the majority of Americans (56 percent) support the ICC and actually believe the United States should become a member. This number grows to 65 percent when Americans are told about how the court is a vehicle for promoting democratic values, such as accountability and human rights. My research indicates that unlike the administration, ordinary citizens are more concerned about the ICC’s fairness and competence — and less concerned about whether U.S. personnel may be investigated.

If Bensouda and her team can demonstrate impartiality and effectiveness in their work, they are likely to enjoy the trust and support of the U.S. public. In turn, this support might put pressure on policymakers to comply with the ICC investigation in the weeks, months and very likely years to come.

Kelebogile Zvobgo (@kelly_zvobgo) is founder and director of the International Justice Lab at William & Mary and a PhD candidate in political science and international relations at the University of Southern California.