“How do you stop these people? You can’t,” Donald Trump said at a rally in Florida in May. The response from someone in the crowd came immediately: “Shoot them.” The audience laughed and cheered. Trump smirked and made a joke about it.

“Them” meant Latino immigrants and refugees that day. “Them,” to those who take Trump’s permission to spread hatred boldly and openly, has at times in the past two years meant Jews, Muslims, Sikhs, Hindus and anyone who stands against the white nationalist agenda.

Since 16 June 2015, the day he rode an escalator down to the lobby of Trump Tower to tell a gathering of paid attendants that he would run for president, he declared that we should fear immigrants from Mexico because they rape, Trump has made fear of immigrants – and those who might look like immigrants – the central theme of his campaigns and his administrative priorities.

Regardless of his tweets and speeches, his actions have inspired and emboldened violent bigots. Trump has gleefully imprisoned migrant children, illegally separating from their families. He has unleashed immigration officers to engage in mass sweeps of immigrant neighborhoods in search of anyone who might lack documentation – often nabbing and detaining US citizens in the process. He has denied legal immigrants such as those seeking asylum the opportunity to enter the country to make their case. And he has directed racist insults at his elected critics (not coincidentally, women) intended to question their loyalty to the United States. And, of course, Trump first entered the political arena by spreading racist lies about President Barack Obama’s citizenship and place of birth.

Regardless of his tweets and speeches, his actions have inspired and emboldened violent bigots

On Saturday a Trump supporter, motivated by a fear that white people were losing control of everything in the United States, was arrested. Police said the suspect opened fire in a department store in El Paso, Texas. Twenty-two people died and 27 more were injured. Most of the victims were Latino. Some were immigrants. Some victims were hesitant to seek medical care because they feared Trump’s crackdown on immigration status.

In the immediate reporting and analyses, some explored the role of the notoriously open discussion forum, 8Chan, which has hosted discussions, declarations and plans for numerous such racially motivated attacks. The suspect had posted a long message to the forum outlining his justifications and plans. Others noted that the Trump campaign has since February run a series of advertisements on Facebook that warn of an “invasion” and declare, against all evidence and with clear malice, that border crossings constitute a threat to the safety of Americans. And, of course, Fox News has played a role in stoking the fear of immigrants that some have used to justify violence.

It’s hard in the heat of the moment, in the face of so much suffering and horror, to look at the entire ecosystem that fosters and encourages such thought and action. But we must. There are no simple, straightforward causes for this phenomenon. There is no simple “solution”. There is not one distinct medium to blame.

As scholars Joan Donovan of the Shorenstein Center at Harvard and Jesse Daniel of the City University of New York have explained, white nationalists are savvy about how they work our dynamic, interconnected media ecosystem. Sometimes the terrorists seem more savvy than the journalists who write about them.

When they post screeds on forums such as 8Chan, white nationalists intend for police and journalists to quote directly from them and spread their messages farther than they could themselves. Their claims and terms of choice leap from the dark recesses of small, discrete groups into wider circulation.

Coverage and quotes echo around mainstream news reports, then get recirculated even farther and revised into vernacular commentary via amateur posts to Twitter, WhatsApp and Facebook. Facebook’s algorithms are designed to amplify content that generates strong emotions – and thus user reactions. Racist violence and the commentary about it tend to do just that. So everyone’s Facebook News Feed fills up with news clips, videos (doctored or not), commentary, jokes and angry expressions.

As individuals add their own perspectives, reaction to these events can then gel into new forms and new expressions via Facebook and Twitter. What rises on Twitter tends to echo on Facebook and vice versa. Soon images and messages are bouncing back and forth, getting picked up by cable news, newspapers and news sites, Twitter users, Facebook users, WhatsApp users and YouTube contributors. Every player in this complex ecosystem enhances, amplifies and changes the story and the message. That media effect, as much as the corpses, inspires these attacks. Like with all terrorism, the spectacle is the reward.

Add to all of that the power of Facebook advertising. Trump’s campaign in 2020, like in 2016, will depend on the ability to run hundreds or thousands of different versions of advertisements, carefully tested and targeted at slim tranches of the potential electorate. Some messages might motivate those otherwise unaccustomed to voting. Others might demotivate someone who would otherwise vote for Trump’s opponent. Facebook’s constant surveillance of us empowers this system, ensuring that most of these ads run beneath public scrutiny. No one sees them except the intended mark.

Trump must consider the deaths of so many innocent people to be a price worth paying for his own power

The fact that so many of Trump’s Facebook advertisements overtly appeal to white nationalism should disgust us. It should also alarm those who run Facebook. How they can go to work each day knowing that they directly profit from the spread of ethnic hatred is beyond me.

For violent white nationalists (and other propagandists) this is an ideal media system. Their numbers can grow once their messages don’t seem so jarring and outside the bounds of normal conversation.

The most dramatic effect of the complex relationship among Trump’s statements, Trump’s policies, Fox News’ fearmongering, mainstream journalism, 8Chan’s collection of misfit manifestos, Twitter obsessions and Facebook commentary, is that the rhetoric of violent white supremacy has become common – almost normal.

And so more people find white nationalism viable, perhaps acceptable. They might be less willing to condemn overt racism. Mainstream journalists and pundits might be more willing to grant racists the benefit of the doubt and take their concerns seriously. More voters might find white nationalism a comfortable world view, one that satisfies a once-latent urge to bond only with those like them and blame problems on those unlike them.

Trump’s racism is old, established and well documented. And the spike in white nationalist visibility and violence since 2017 is unambiguous. That does not mean Trump wishes slaughter on those he despises. He might even wish he could get away with his statements and policies without having to face the tirades and admonitions that follow each successive incident of racist violence in America.

Yet Trump tolerates the sort of violence we saw in El Paso on Saturday. He easily tolerated the violence that engulfed the streets of my town, Charlottesville, Virginia, just eight months after he took office. After each incident in between those two, Trump resumed inflaming racist passions among his followers within days.

Trump must consider the deaths of so many innocent people to be a price worth paying for his own power.

Over time, the normalization of white nationalism weakens criticism within his own party and attracts many who might otherwise be alienated from a more humane political culture. It also strengthens the resolve of many of his supporters who see their families and identities under threat.

Trump’s campaign to retain the White House in 2020 is already distilled into a series of messages about how his supporters should fear people from other places. His campaign rallies and advertisements reveal his core goal: to stoke fear and anxiety among potential supporters so they turn out to vote in large numbers and do not waver in their support of their own kind. That’s the only way he can come close to winning. And even if Trump loses he does so with a rabid pack of committed supporters howling for revenge, eager to unleash new furies on the rest of us. Either way, Trump’s ego swells.

Trump is a politician perfectly fitted for a media ecosystem that amplifies extreme emotions, resists complex or nuanced thought, impedes deliberation and allows the loud to drown out the calm. Like Rodrigo Duterte in the Philippines, Narendra Modi in India, Jair Bolsonaro in Brazil, Matteo Salvini in Italy, and Viktor Orbán in Hungary, Trump has leveraged fear and hatred to drive his extreme nationalism to power.

Unless we can forge a strategic global movement to challenge their vision of pure and intolerant nations, the entire world will suffer from more trauma. Meanwhile, in the United States, where it’s easier to acquire a semiautomatic weapon than a puppy, things will get worse before they get better.