Minnesotans awoke on a recent Saturday to reports that an assassin had spent the night ticking his way down a list of Democratic targets, wounding one state lawmaker and his wife and then, just as the police closed in, killing another, along with her husband and their dog.

It was shocking. But it quickly seemed to become just another episode in a recent spate of political violence. Since last July, two people have tried to assassinate Donald Trump; an arsonist set fire to the Pennsylvania governor’s mansion while the family slept; an assailant fatally shot a couple leaving the Capital Jewish Museum in Washington; and a man was charged with attempting to kidnap the mayor of Memphis, Tennessee.

The result is a troubling sense that political violence has become more brazen, and its motives more difficult to comprehend. The increase is not just public perception; experts agree that attacks on political figures have been increasing.

The Armed Conflict Location & Event Data project, a nonprofit group that tracks conflicts around the globe, has recorded 21 acts of violence against politicians, their families or their staffs in the United States since it began counting them in 2020. A vast majority have occurred since 2022.

The rise comes as vicious and dehumanizing language and images become common in American politics. Online culture is a potent vector, seeming only to amplify rather than calm or contextualize, while offering plenty of encouragement to would-be imitators. And guns have been deregulated in many states, becoming easier to acquire.

Political violence can encompass a broad range of actions, from torching Tesla charging stations to premeditated sniper attacks, making it difficult to quantify.

And violence motivated by racial, ethnic and partisan differences has been part of the American storyline from the beginning. Those annals include the terror campaigns of the Ku Klux Klan, the anarchist bombing of Wall Street in 1920 and the gunning down of police officers by the Black Liberation Army in the 1970s — all violence that had societal or even revolutionary aims.

In contrast, American political violence today is more likely to be carried out by someone acting alone, in despair and deeply dosed on the steroidal forms of extremism offered by the internet.

Such attacks can seem infused with futility from the outset, said Shuki Cohen, who studies terrorism and political violence at the John Jay College of Criminal Justice. The new ideology is nihilism itself, he said, “just a vague doomsday mentality of burn it all down and go out in a blaze of glory.”

Perpetrators exhibit “learned helplessness,” he said, a sense that the political system is incapable of averting the jumble of apocalyptic scenarios cited in their manifestoes: climate change, unregulated artificial intelligence, concentrated wealth, nuclear threat and society’s moral collapse.

Sometimes it is possible to draw a straight line between ideology and action. Vance Boelter, the man accused in the Minnesota attacks, was a conservative Christian who opposed abortion and targeted liberals. Luigi Mangione, accused in the shooting of a health insurance executive on a New York City street last year, was a critic of the American health care system. And there’s Guy Edward Bartkus, who officials say detonated a bomb outside a fertility clinic in Palm Springs, California, in May, in the apparent belief that humans should voluntarily become extinct.

But the motive of Thomas Crooks, who attempted to assassinate Trump at a campaign rally in Butler, Pennsylvania, last July, was a riddle. He had done internet searches for Trump and Joe Biden, seeming to have chosen his target almost at random. He had no “definitive ideology,” the FBI concluded, but he did have an AR-15-style rifle. Does that count as political violence, or just American violence?

“Those sorts of incidents, where we can’t figure out why they did it, are becoming more common,” said Katherine Keneally, the director of threat analysis and prevention at the Institute for Strategic Dialogue, a nonprofit that works to combat extremism.

Of course, America’s legacy of political violence is littered with all manner of motives. John Wilkes Booth was part of an organized conspiracy that opposed President Abraham Lincoln’s views, but the killer of President James A. Garfield, less than 20 years later, became a landmark case for the insanity defense, said Adam Goodheart, the director of the Starr Center for the Study of the American Experience at Washington College.

The United States has long glamorized violence. It has a higher homicide rate than other developed Western nations, and mass shootings have become routine. Recently, threats against public officials have soared. The number investigated each year by the Capitol Police, who protect federal lawmakers, has more than doubled, rising to 9,474 last year from 3,939 in 2017. Threats against judges have spiked dramatically since Trump returned to office, according to data from the U.S. Marshals Service.

On the other hand, experts say the threat of violence by right-wing extremist groups, which have long been behind most domestic terror attacks, began to recede before Trump won the election, in part because their leaders were prosecuted after the Jan. 6, 2021, attack on the Capitol, and in part because of expectations that Trump would win.

“In some periods, you don’t need political violence,” said Dan Byman, the director of the Warfare, Irregular Threats and Terrorism Program at the Center for Strategic and International Studies. “The Klan, strangely enough, was weaker in Mississippi in the ’60s than it was in North Carolina. Which might seem odd, but the reason is if you were racist, the government of Mississippi was doing exactly what you wanted.”