Most Americans were shocked to learn about the massacre of 50 people at two mosques in Christchurch.
They shouldn't be.
The violent strain of white nationalism that appears to have inspired the alleged gunman has grown increasingly pervasive and strident in the US during the past several years.
At its core, white nationalism is about fear - a sense of white vulnerability and weakness - that nonwhites are "invading" a nation and seeking to usurp power and privileges that rightly belong to white people.
Such fear-driven narratives give white nationalism its power to radicalise, fuelling violence against an "invading other" - even a person who might, in a different era, have been perceived as allies in the fight for white supremacy.
Most Americans are quick to write off white nationalist conspiracy theories and violence as something on the fringes of society or perpetuated by an alienated few or by those in need of mental health treatment.
The reality is that white nationalism - even the violent variety - has been a central feature of mainstream American culture at various points in the country's history.
Unless Americans, including our leaders, are vigilant and clearly draw moral lines, it could easily return to the cultural mainstream in the future.
Racial nationalist hatred and violence reached its peak during the World War I era. Americans in the early 20th century, particularly those who identified as a white "Anglo-Saxon," tended to view their world through the intersecting paradigms of race and progress.
White Western nations, the United States included, used what then passed as science to explain their superior cultures, economies, education, militaries and imperial domination of "lesser" beings. The extent of a nation's (or race's) advancement was regularly understood to be a function of biology. The result was scientifically sanctioned hierarchical racism, which placed the peoples of the world on a scale with the white races of Western Europe and the United States invariably at the top.
During this period, immigrants from the less modernised nations of southern and Eastern Europe, who were arriving to America at record rates, were largely marginalised despite their apparently white skin.
Aliens were more often depicted by politicians and the press as invading hordes that threatened to undermine the democratic and capitalist order than as individuals capable of assimilating into Anglo-Saxon culture.
Germans, by contrast, were viewed by white Anglo-Saxon Americans before the war as racial kin, fitting them squarely on the "civilised" portion of the scale. The coming of the Great War and the anxiety it engendered, however, drastically altered the ways in which race-conscious white Americans viewed their Teutonic neighbours and Germans in Europe.
In part, this was the result of actual events: small-scale German sabotage, espionage and propaganda; the sinking of neutral ships and the tragic killings of civilians on the high seas by German submarines, and the defilement of Belgian and French civilians and their property by the German army. These events and actions suggested to many Anglo-Saxon Americans that something was off about the once-respected German race.
To make sense of their German enemy, white Americans fell back on their understanding of the linked nature of race and progress. When German wartime actions were reframed within the context of race, the German people began to take on a shape that fit closely with stereotypes of the most prominent "others" that had haunted the nightmares of anxious whites: the crazed, bomb-throwing foreign labour radical and the docile yet lecherous African-American.
The Teutonic race, many white Americans concluded, had regressed into a more bestial, aggressive and duplicitous state. Long-held nativist anxieties about white vulnerability allowed Americans to strip their white German enemy of its "whiteness" and thus transform it into a dangerous, nonwhite, threatening other.
Wartime propaganda only reinforced this interpretation. Government and private propaganda agencies along with the press inundated nervous Americans with posters, speeches, editorials, cartoons, advertisements and films warning of dastardly German American spies and saboteurs as well as the likelihood of brutish and lustful German soldiers landing on American shores and re-creating the raping and pillaging of Belgium in the United States. Such messages struck an exposed nerve in white Anglo-Saxon culture, a world already ill at ease over the massive demographic shock of recent immigration.
During the war, many white Americans - in the name of defending the national community from dangerous less-than-white outsiders - acted on their nativist anxieties with extralegal violence. In every region of the country, German-Americans and their supposed immigrant socialist allies were beaten, publicly humiliated, stripped of their property and, in a few cases, lynched.
American leaders, President Woodrow Wilson's Administration in particular, responded to white vigilantism with indifference or justified the violence by blaming it on the weakness of federal sedition laws that allowed enemy agitators the freedom to spread the enemy's gospel. Wilson's white supremacist beliefs and his Administration's consistent endorsement of German otherness are probably explanations for his apathy. Nationalist violence was protected by the nationalist wartime state.
The official tolerance of and slow response to nativist attacks by the country's leaders opened the door to more extreme white nationalist causes after the war, such as the "100 per cent Americanism" of the postwar Ku Klux Klan and the excesses of the first Red Scare.
Today, we live in a generally more tolerant and empathetic time. New Zealand Prime Minister Jacinda Ardern bluntly declared that the Muslim victims of Friday's mass shooting "are us," in sharp contrast to the relative silence emanating from the White House during World War I.
But we also live in a time of rising violent white supremacy.
In recent years in the United States, American white nationalists have been aggressively on guard against what they envision to be existential threats to white power.
This revival of violent white supremacy, according to a report by the Southern Poverty Law Centre, has been framed as a response to demographic changes.
The Census Bureau projects that, within the next 25 years, whites will no longer comprise the majority of the US population.
White nationalists have fuelled fears of this perceived threat to draw more members to their movement and inspire more acts of racist violence.
In late 2018, the FBI reported hate crimes had increased by 17 per cent from the previous year. Of the nearly 7200 hate crimes the FBI recorded, roughly 60 per cent were racial or ethnic in nature.
Before carrying out his attack, the suspect in the massacre at the Tree of Life synagogue in Pittsburgh in October justified his act online by citing an imagined Jewish conspiracy to transport Central American refugees into the country - the infamous "caravan" - for the purpose of murdering large numbers of white people.
The internet enables twisted perpetrators to trade in these falsehoods, and to engage with communities that embolden them and heighten their sense of being under attack.
There are signs that some of our leaders are not taking the white nationalist threat seriously enough.
After Friday's attack, US President Donald Trump dismissed white nationalism as simply a case of "a small group of people" with "very, very serious problems".
Yet there can be no doubt that white nationalism is on the rise in the West. As the case of the US during World War I indicates, we minimise such violent ideologies at our own peril.
The challenge is to ensure racial nationalism does not find its way back into the mainstream.
- Smith is the author of Age of Fear: Othering and American Identity during World War I. He teaches writing and rhetoric in Birmingham, Alabama.