But as investigations proceed and Americans consider these revelations, they should hold in mind another transgression: the president’s egregious mistreatment of one of the country’s most distinguished ambassadors. Even before the rough transcript of the call between Trump and Ukrainian President Volodymyr Zelensky was released, we knew that the administration had prematurely curtailed the appointment of U.S. Ambassador to Ukraine Marie Yovanovitch following public attacks on her by the president’s eldest son and by his personal lawyer, Rudolph W. Giuliani. Administration officials then falsely claimed that she was leaving her post “as planned.” Now, we also know that Trump went on to denigrate the ambassador in a phone call to a foreign leader, telling Zelensky that “the woman” was “bad news” and vaguely but ominously noting that “she’s going to go through some things.”

Presidents are entitled to have their own ambassadors in place and to expect those ambassadors to implement their policies. But the consequences of Trump’s apparent willingness to punish a top U.S. representative, and to disparage her in a conversation with a foreign government, should not be underestimated. Allowing this to stand would not only have a chilling effect on the entire diplomatic corps but also could undermine U.S. foreign policy more broadly.