Six former US officials with esteemed careers in diplomacy and prosecuting war crimes issued a brief but forceful statement Wednesday criticizing Secretary of State Mike Pompeo’s response to recent actions at the International Criminal Court (ICC).

Earlier this month, ICC prosecutors won an appeal allowing them to continue an investigation into war crimes during the “Afghanistan situation,” or the prolonged conflict in that country that began in 2003. The parties on which the prosecutors will focus their investigation are the Taliban and its affiliates, the Afghan National Security Forces, and the US armed forces and intelligence agencies.

In response to the news at the ICC, Pompeo issued what Wednesday’s letter-writers called “crude threats” that “debase America’s commitments to the rule of law.” On Tuesday, Pompeo called the ICC a “so-called court,” called out by name the two prosecutors investigating Afghanistan, and insinuated that he may target them or their family members with punitive sanctions. The letter’s authors, including Benjamin Ferencz, who famously prosecuted war crimes at the Nuremberg trials following World War II, and several former ambassadors and officials with careers addressing war crimes, called Pompeo’s threat “reckless and shocking in its display of fear rather than strength.”

Such words “can only undermine the confidence of those around the world who look to the United States for leadership and inspiration to protect the victims of the world’s worst atrocities,” the authors stated. The brief letter concludes by noting that the US could interact with the ICC in a less crude and intimidating manner, such as under the procedures outlined by the treaty that governs the court. “Such an act of confidence by Secretary Pompeo would far better protect U.S. interests than the kind of threat issued yesterday,” the authors wrote.