AMNA NAWAZ: The shootings of two Minnesota lawmakers and their spouses this weekend are just the latest instances of targeted political violence in America, a trend experts say is being exacerbated by increased polarization and heated rhetoric from public figures.

William Brangham joins us now with more.

WILLIAM BRANGHAM: Amna, as you say, these disturbing acts are part of a pattern that we have seen playing out over the last few years, a congressman at a baseball practice, the family of the former speaker of the House, Pennsylvania's governor, and candidate Donald Trump all targets of graphic political violence.

To help us better understand the root causes and potential solutions for this, we are joined again by Cynthia Miller-Idriss.

She's a professor at American University and the author most recently of "Man Up: The New Misogyny and the Rise of Violent Extremism."

Cynthia Miller-Idriss, so good to have you back on the program.

Before we get into this broader trend, I want to ask you about this attack over the weekend in Minnesota.

We know that the alleged suspect there targeted Democrats and their spouses, and his list of potential victims were also all Democrats.

Is there anything else about his history that gives us some clues as to his motivations?

CYNTHIA MILLER-IDRISS, American University: Well, thanks for having me.

It's good to see you again, William.

The history of this particular attacker included some very anti-LGBTQ statements and very strong anti-abortion stances, including language in a speech in sub-Saharan Africa that depicted sort of gendered changes in the U.S. as motivated by the enemy, like the enemy has seeped into their souls kind of language.

So what you see is somebody who is motivated not just to attack progressive causes or politicians, but also really saw gender and women's reproductive rights and LGBTQ issues as a kind of existential threat.

WILLIAM BRANGHAM: And is that a more common theme that emerges with these kinds of attackers?

CYNTHIA MILLER-IDRISS: I mean, it's so common that it's shocking how often we silence it or ignore it, to be honest.

It's very hard to think of an example of a mass shooter or terrorist attacker in American history over the last two decades that did not involve some prior history of domestic and intimate partner violence, anti-LGBTQ statements, harassment, stalking.

So, everyone from the Parkland school shooter to the Uvalde, Texas, shooter, to the Maryland newsroom attacker, just to name three examples that often aren't included in that, had some history of gendered, misogynistic or sexist actions.

WILLIAM BRANGHAM: In an op-ed that you published recently, you talked about increased political polarization as being a big driver of this violence as well.

What does that mean, practically speaking?

CYNTHIA MILLER-IDRISS: Practically speaking, the biggest problem that we're seeing is the use of language that demonizes the other.

And this happens both on the Republican and the Democratic side, but particularly using language like describing the other as evil, as demonic, as an existential threat to the country, to the future of democracy, or as the enemy within, to use language that President Trump has used in his campaign period of time leading up to the election.

That's really the kind of language that can make it seem like someone feels like they have to take action, they're compelled to take what they think is heroic action or patriotic action.

WILLIAM BRANGHAM: In fact, we saw in response to this Minnesota shooting, several conservatives employed that exact kind of language.

They seem to be doing the exact thing you're saying exacerbates violence.

CYNTHIA MILLER-IDRISS: Yes, there's an absolutely right way, unequivocally right way to respond to acts of political violence like this across the partisan spectrum.

What we need is immediate condemnation of violence.

So we did see that from President Trump.

We did see an immediate statement, but a lot of other leaders, we have seen that kind of rhetoric that continued to demonize or paint it as if it were deserved.

And we saw that when President Trump's first assassination attempt happened too.

We saw language like, you reap what you sow, right?

That kind of language that says political violence is somehow justified or valorizes it or blames the other is extremely dangerous.

WILLIAM BRANGHAM: But as any student of American history knows, we have a long history of this, civil wars, lynchings, assassination attempts.

Is there anything unique to this moment in your mind?

Or is this just part of our long, dark history?

CYNTHIA MILLER-IDRISS: We have a long, dark history of political violence, and we have had periods of time like this before, when you think about the assassinations of Martin Luther King or Kennedy, right?

The political assassinations of the 1960s is the kind of thing that we're seeing now.

I think what's different is that this is part of an uptick that dates back about 20 years.

We now see a 2000 percent increase in targeted violent plots over the past 20, 25 years.

That's now three plots a day, according to data from the University of Maryland START Center.

That's different than what we saw 20 years ago.

So we're in a cycle in which this isn't the only time we have had it, but we're definitely in a more dangerous and high-risk environment for political violence.

WILLIAM BRANGHAM: All right, that is American University's Cynthia Miller-Idriss.

Always great to talk with you.

Thank you so much.

CYNTHIA MILLER-IDRISS: Great to talk with you, William.

Thank you.