Other terrorists, including those who conducted deadly attacks on the Boston Marathon, Fort Hood, a military installation in Chattanooga, and a cartoon contest in Garland, Texas, also drew inspiration from the grimly charismatic Awlaki.

Awlaki inflamed tensions by pitting Muslims against Americans. “We are two opposites that will never come together,” he once said. “What they want can only be accomplished by our elimination. Therefore this is a defining battle.”

Domestic terrorists, like their international counterparts, respond to inspirational triggers. FBI Director Christopher Wray testified recently that a majority of this year’s domestic terrorism cases involving a racial motive were thought to have been tied to white-supremacist ideology. For a charismatic leader, those who subscribe to this hateful worldview need look no further than the president of the United States.

I doubt that Donald Trump’s intent is to incite violence, but even if his goal is merely to promote his political interests, by stoking racial discord he may be playing the same role for domestic terrorists as Awlaki did for international terrorists. Trump’s public remarks don’t amount to crimes, but they are irresponsible uses of the president’s bully pulpit.

The list of offensive statements is long. Trump has referred to immigrants from Mexico as “thugs” and “animals” who are part of “an invasion” of the United States. He told four congresswomen of color to “go back” to the “crime infested places from which they came”—never mind that only one of the four was born outside the United States, and that all four are, of course, American citizens.

At a May rally in Florida, Trump discussed immigration, saying, “How do you stop these people? You can’t.” When someone in the crowd yelled “Shoot them,” the crowd cheered. Trump did not attempt to tamp down such talk. Instead, he encouraged it, smiling and saying, “Only in the Panhandle can you get away with that statement.”

Some people find these statements offensive; others find them insightful. For still others, the words apparently fuel violence. On Monday, a judge sentenced Cesar Sayoc, also known as the MAGA bomber, to 20 years in prison. Sayoc mailed 16 pipe bombs to critics of Trump before the 2018 midterm elections; his attorneys said that after being a “loner” and an “outcast,” he “found light in Donald J. Trump.”

Sayoc’s plot failed—but the mass shooting in El Paso, Texas, over the weekend may also lead back, on an inspirational level, to the president’s rhetoric. Police suspect that the killer is the author of an online manifesto expressing hatred for immigrants, and Latinos in particular. Although the author wrote that he has held these beliefs since before Trump was elected, it is only now that he has acted on them.

Terrorists don’t necessarily belong to an organized group or attend meetings. In what the Department of Justice calls “crowdsourcing,” terrorists simply communicate with like-minded individuals on internet forums and social media. They share ideas and normalize one another’s behavior. If someone else is echoing deviant thoughts, the ideas sound less deviant. If that someone else is in a position of authority, like the president of the United States, the effect is more dramatic.