The Trump administration’s latest step to prevent the International Criminal Court from investigating war crimes in Afghanistan was announced Friday by Secretary of State Mike Pompeo, but it’s hard not to see it as the result of national security adviser John Bolton’s influence.

Pompeo announced a “policy of U.S. visa restrictions on those individuals directly responsible for any ICC investigation of U.S. personnel” and said the administration was already implementing the policy, though he would not name any individuals involved. He cited the authority granted to the secretary of state under the 1990 Immigration Act to bar individuals whose presence “would have potentially serious adverse foreign policy consequences for the United States.” He also said the policy could be used to deter investigations of allied personnel, including Israelis, and said further steps could include economic sanctions.

Bolton previewed these steps in a speech in September. Bolton, a longtime opponent of the court, sees the ICC as a dangerous threat to American sovereignty as well as, somewhat contradictorily, an ineffective and redundant organization. He has called his work to push back against it under the George W. Bush administration “one of my proudest achievements.”

While this is a longtime fixation of Bolton’s, the State Department’s actions Friday were specifically prompted by ICC Prosecutor Fatou Bensouda’s November 2017 request for a formal investigation into war crimes committed in Afghanistan. ICC investigations look at all actions in a given country rather than those of a particular actor, so this one could include alleged crimes by the Taliban and Afghan government forces as well as the U.S. military. While the U.S. is not a party to the ICC, Afghanistan is, so actions committed there fall under the court’s remit. However, the court’s ability to enforce that remit is notoriously weak, and it’s very unlikely U.S. troops would ever actually go on trial at The Hague. In any event, no significant action has been taken on the Afghanistan case since Bolton’s speech—judges are still weighing the evidence to decide on Bensouda’s request—so it’s not quite clear what prompted this latest escalation. Pompeo said only that it was unacceptable that “the prosecutor’s request for an investigation remains pending.” One of the ICC’s judges quit the court in January, partially in protest of the pressure by the Trump administration.

It’s worth noting that U.S. law already includes restrictions on ICC agents. The American Servicemembers Protection Act, an anti-ICC measure Congress passed in 2002, already prohibits ICC agents from conducting any inquiries or investigations on U.S. soil. The new policy takes things a step further, since ICC personnel are apparently being barred before an investigation has even begun.

The ASPA has been nicknamed the “Hague Invasion Act” by opponents because of a clause that authorizes military action to rescue any U.S. citizens who have been detained for prosecution by the court. That used to seem like a far-fetched scenario.