We will never know precisely why a 29-year-old American went to a gay nightclub in Orlando, Florida, and started shooting people. It was a hate crime, obviously, but was it driven by more than homophobia?
The man was the son of immigrants from Afghanistan, he had sympathies with Isis and reportedly pledged allegiance to the "Islamic State" in a 911 call he made from the nightclub. His former wife says he was mentally ill.
If he must be called a "terrorist" he seems a particularly solitary one. There was no co-ordinated action, as there has been in Paris and Brussels, no suggestion of a jihadist cell in Orlando.
He had previously expressed sympathy for a suicide bomber, which caused him to be interviewed by the FBI in 2013 and again in 2014, but obviously the bureau did not consider him dangerous enough to warrant surveillance. After he was killed by police in the nightclub where 50 people lay dead and another 50 or more had been injured, a message was posted on a jihadist website calling the attack the work of "an Islamic State fighter".
But it would say that.
How easy it becomes for Isis to gain an inflated image of global importance from what are probably random acts of deranged individuals who invoke its name for their own sense of self-importance.
The United States makes this particularly easy because it lets a young man such as Omar Mateen buy a pistol and an assault rifle with few questions asked, and the politicians who defend these insane gun-owning rights are always willing to paint the threat of Isis in the most fearful tones.
The latest incident ranks as the deadliest mass shooting in the United States so far and it is being called the nation's worst terror attack since 9/11, but it differs only in the number of dead from countless other mass shootings that have not claimed an Islamist connection. Statistically Americans are still far more likely to be killed by one of their own, taking advantage of his constitutional rights, than by agents of foreign terror. But President Barack Obama is tired of telling them so.
Typically and tastelessly, Donald Trump was quick to take advantage of the incident yesterday, tweeting that he "appreciated the congrats on radical Islamic terrorism" and disingenuously adding, "I don't want congrats, I want toughness and vigilance. We must be smart." His immigration ban on Muslims would not have made any difference in this instance - Mateen was born in the US to Islamic immigrants who have been law-abiding Americans for at least 30 years.
They and fellow Muslims do not deserve the politics of Mr Trump. But if his purpose is to alienate and further radicalise a younger Muslim generation, he is probably succeeding. Coupled with the gun laws that just about all Republicans endorse - and too few Democrats dare to oppose - the US is doing itself no favours.
President Obama reminded his nation yesterday that the victims of this killing were gay. If any Americans were terrorised yesterday it was those whose sexual orientation could be such a target. That is the worst of it.