Donald Trump tweeted about the terrorist attacks in Paris in November 2015 about 3½ hours after they occurred. The next month, he tweeted about the mass shooting in San Bernardino, California, 90 minutes after the violence began. It took less than 12 hours from the time an EgyptAir flight went missing in May 2016 for Trump to speculate publicly that the attack was terror-related. More than a year later, it is still not clear what happened to the aircraft.

When terrorists drove a van into a crowd on London Bridge this month, Trump tweeted about the need to be “smart, vigilant and tough” even before authorities identified terror as the motive behind the attack.

About 15 hours ago, as of this writing, a man drove a van into a group of Muslims near a mosque in London. The attack, which killed one person and injured ten others, is being treated as terror-related by authorities in Britain. Prime Minister Theresa May described the attack as “every bit as sickening” as the attacks at the London Bridge and, in March, on Westminster Bridge.

Trump tweeted his condolences to the victims of those two earlier attacks — both linked to the Islamic State — the same day they happened. Trump has not tweeted about Sunday night’s attack on Muslims.

In response to a crisis, one of the simplest responses from a president is a carefully worded statement of support, condolence or outrage. Simpler still is a brief message on social media.

Trump built his political career in part on his willingness to jump into any number of frays by tweeting about them. As we have noted in the past, he shows little reticence to tweet about things he sees on television right after he sees them. Yet, Monday morning: silence.

Trump’s use of Twitter betrays his interests and disinterests. On Sunday, Father’s Day, Trump tweeted, in order:

• A two-part defence of his political success

• An outlier poll showing him as more popular than he is

• A retweet of the performers Diamond and Silk criticising the media

• A retweet of his son being critical of former President Barack Obama

• Praise for Camp David, where he spent the weekend

• A retweet of the White House’s “Happy Father’s Day” message that morning

That Trump has not mentioned the attacks on Muslims in London is not surprising. It took days for him to praise the two men who were stabbed to death in Portland, Oregon, while defending Muslim women on a train. It took almost a week for him to speak out about the shooting of two Indian men in Kansas by someone who thought that they were Muslim. In one sense, it is odd that Trump has not tweeted condolences to the victims in London, given the criticism he has received for his slow response to the earlier-mentioned attacks — but, again, it is not surprising that he has not, given his history.

The broader question is why Trump remains uninterested in acknowledging such attacks.

One likely explanation is that Trump sees attacks by people of the Muslim faith through the lens of a rampant anti-Western ideology, but views attacks on Muslims as being one-off examples of bad actors. The emergence of al-Qaeda and the Islamic State reinforced the idea that there is a substantial, organised subset of the world’s Muslim population focused on political violence. Absent those groups, attacks such as the one on Westminster Bridge or at Orlando’s Pulse nightclub might more easily be treated as aberrant individual actions in the way that the attack on Muslims in London will be treated in some quarters. That there is a strong but largely disorganised anti-Muslim undercurrent in Western societies that can make Muslims a target of violence lacks the sort of readily identifiable markers as a co-ordinated terror group, especially for those unwilling to see them.

In June 2015, when a white gunman shot nine black worshippers dead at a church in Charleston, South Carolina, shortly after Trump announced his presidential candidacy, Trump tweeted about it.

“The tragedy in South Carolina is incomprehensible. My deepest condolences to all.”

— Donald J. Trump (@realDonaldTrump) June 18, 2015

It was incomprehensible in the sense that murdering nine people at church is an affront to our sense of humans as rational creatures. It was entirely comprehensible in the sense that a white man who held racist views may target black people in a shooting spree.

To view attacks by Muslims as part of what being Muslim is about, but attacks on Muslims as being distinct from the identities of the perpetrators demands seeing those two groups as fundamentally different. Trump has a presumption of guilt for Muslims that he does not have for the white people who committed the crimes in Kansas, Portland and at the London mosque.

It is interesting to compare Trump’s response to the Charleston shooting with his response to the 1980s rape of a white woman in Central Park, for which a group of black and Hispanic teenagers were arrested and which prompted Trump to buy a full-page advertisement calling for the death penalty for the accused.

Those teenagers were later exonerated when another man admitted to the crime. But Trump, even as recently as last October, seemed to believe that the teenagers were the perpetrators. “They admitted they were guilty,” said Trump, who elided the critical point that the confessions were obtained under duress. “The police doing the original investigation say they were guilty.”

In Trump’s eyes, those teenagers are guilty despite the judicial system rescinding that verdict.

Trump’s presidential campaign, and therefore his presidency, relied on the idea that America was under threat from terrorism and crime, a point of view that necessarily overlapped with America’s complex racial history. That is the other reason Trump highlights terrorist acts by Muslims and ignores those against them: he has reaped political rewards from it.

Trump views terrorism through a very particular lens, and he won the presidency by articulating that lens. That it is reflected in his Twitter account, then, is not a surprise.

• Philip Bump is a correspondent for The Washington Post based in New York City