Unrepentant, Republican Rep. Paul Gosar remained defiant about posting a violent anime video depicting him killing his colleague, Democrat Alexandria Ocasio-Cortez, as well as brandishing swords at President Joe Biden.

Unlike the fate he would have faced in nearly any other workplace, Gosar was not fired (expelled, in congressional parlance), but instead censured on a nearly pure party-line vote, with some Republicans identifying other incendiary individuals like Democratic Rep. Maxine Waters for inciting demonstrators to "get more confrontational" if a Minneapolis jury acquitted Derek Chauvin. (Republican Reps. Liz Cheney and Adam Kinzinger, profiles in courage in demanding accountability for the Jan. 6 attacks, voted with Democrats.)

After well wishes from congressional Republicans backing the Arizonan, Gosar (who later retweeted the offending video) left the chamber wearing an American flag face mask.

The image was fitting. Because as a new study and news headlines attest, Gosar's actions were just the latest unmasking of the threat and tragically the reality of rising political violence in America.

"From death threats against previously anonymous bureaucrats and public-health officials to a plot to kidnap Michigan's governor and the 6 January 2021 attack on the U.S. Capitol, acts of political violence have skyrocketed in the last five years," wrote Rachel Kleinfeld in "The Rise of Political Violence in the United States," an article that ran in the Journal of Democracy.

"The nature of political violence has also changed," Kleinfeld, a senior fellow in the Democracy, Conflict, and Governance Program at the Carnegie Endowment for International Peace, added. "The media's focus on groups such as the Proud Boys, Oath Keepers, and Boogaloo Bois has obscured a deeper trend: the 'ungrouping' of political violence as people self-radicalize via online engagement."

To some, that last category could include Kyle Rittenhouse, who was acquitted on all counts in his high-profile trial in Wisconsin on Friday.

To others, the defendant was the victim in a case that became just the latest Rorschach test of a nation riven with divisions.

These divides are inclusive of and amplified (or even created) by a fragmented media landscape that Kleinfeld suggests is seeping into mainstream media sources.

"Ideas that were once confined to fringe groups now appear in the mainstream media," she wrote. "White-supremacist ideas, militia fashion, and conspiracy theories spread via gaming websites, YouTube channels, and blogs, while a slippery language of memes, slang, and jokes blurs the line between posturing and provoking violence, normalizing ideologies and activities.

"These shifts have created a new reality: millions of Americans willing to undertake, support, or excuse political violence."

Including one whose words have extraordinary force: former President Donald Trump, who endorsed Gosar after his censure, and was heard in audio released this week explaining Capitol insurrectionists' invective against former Vice President Mike Pence.

"I thought he was well-protected, and I heard that he was in good shape," Trump told journalist Jonathan Karl when asked about the MAGA mob's chants of "Hang Mike Pence."

Well, Trump continued, "the people were very angry. Because it's common sense, Jon. It's common sense that you're supposed to protect. How can you — if you know a vote is fraudulent, right? — how can you pass on a fraudulent vote to Congress?"

The "false narrative of a stolen 2020 election clearly increased support for political violence," Kleinfeld wrote, adding that believers in lies like this "were far more likely to endorse coups and armed citizen rebellion."

This fits into a global pattern of four factors that elevate the risk of election-related violence, according to Kleinfeld: 1) a highly competitive election that could shift the balance of power; 2) partisan division based on identity; 3) electoral rules that enable winning by exploiting identity cleavages; and 4) weak institutional constraints on violence, particularly security-sector bias toward one group, leading perpetrators to believe they will not he held accountable for violence.

The U.S., like other countries in this combustible era, have a degree of each of these factors. It's one reason why so many are anxious about aftermath from the Rittenhouse trial and a concurrent courtroom drama in Brunswick, Ga., over the killing of Ahmaud Arbery. In particular, the partisan-identity nexus in America has intensified in recent years. Referencing the work of political psychologist Lilliana Mason, Kleinfeld writes that "greater homogeneity within groups with fewer cross-cutting ties allows people to form clearer in-and-out groups, priming them for conflict." And often the feelings are "personal, and thus more powerful. These real cultural and belief differences are at the heart of the cultural conflicts in the United States."

These cultural chasms over vaccine and mask mandates, what's taught at schools (often facilely and falsely oversimplified as critical race theory) and other highly divisive issues can make the public square look like a ring, with school board members and election and public health officials facing hostility, even harassment. (They were vital to the victory of Republican Glenn Youngkin in Virginia's gubernatorial race, too.)

In her article, Kleinfeld rightly points out political violence's "long history" in the United States and said that since the late '60s "it was carried out by intensely ideological groups that pulled adherents out of the mainstream into clandestine cells." Which seems to reflect another big story this week: the exoneration of two men convicted in the 1965 killing of Malcom X.

"Violent fringes were mostly on the far left" in the late '60s and '70s, Kleinfeld wrote, explaining "extensive violence, largely against property (with notable exceptions), in the name of social, environmental, and animal-rights causes." This shifted in the late '70s, moving rightward with rising violence from "white supremacist, anti-abortion, and militia groups."

Politically inspired violence clearly continues from the left, as seen in several significant cities like Portland and Seattle (and certainly here at home) during the last two years. Deploying data, Kleinfeld argued in her article and said in a webinar on Thursday that the spike is "pretty much on the far right." There's "really no comparison," she said, rejecting "bothsideism" that she claimed data doesn't support.

Among the key data points is a stark chart based on the Global Terrorism Database. In 2000, the highest number of attacks, about 23, were attributed to "environmentalists," with "single issue" attackers second with about a dozen attacks. Those categorized as "religious," "far left" and "far right" were in the single digits. By 2019, all categories were in the single digits, but the "far right" exceeded 50.

Americans cannot be numb to these numbers. Our governance, our civil society, depends on civility itself. Disagreement is to be expected and accepted. Threats, or actual violence, cannot be.

Speaking at the censure debate, Ocasio-Cortez plaintively appealed to House Minority Leader Kevin McCarthy.

"What is so hard about saying this is wrong?" she asked, adding, "This is not about me. This is not about Representative Gosar. This is about what we are willing to accept."

As a Congress, yes.

But also as a country.