The United States has a serious problem with political violence, particularly right-wing violence, which has overtaken Islamist attacks as the No. 1 domestic terrorism threat. The list of right-wing outrages includes Oklahoma City 1995 (168 dead), Pittsburgh 2018 (11 dead) and El Paso 2019 (23 dead). The 2020 Kenosha, Wis., shooting, which left two dead, is part of the same alarming trend. Even though Kyle Rittenhouse was found last week to have acted in self-defense, he remains morally culpable for showing up with an assault-style rifle at a protest, looking for trouble.

In many other instances — e.g., the 2018 pipe bombing attempts targeting critics of President Donald Trump — tragedy was only narrowly averted. The Jan. 6 riot was both horrible and not nearly as bad as it could have been: Though 140 police officers were injured in the worst assault on the Capitol since the War of 1812, the insurrectionists did not succeed in killing or kidnapping any lawmakers.

Faced with this alarming trend, a responsible political party would damp down its incendiary rhetoric and urge its supporters to moderate their zeal. That is not what Republicans are doing. They continue to fan the flames of hatred, violence and division.

Many on the right routinely depict Democrats as America’s enemies. At one recent conference, Sen. Ted Cruz (R-Tex.) said, “The left hates America,” while Sen. Josh Hawley (R-Mo.) said: “Their grand ambition is to deconstruct the United States of America.” At the same time, Republicans make a fetish of gun ownership and use; weapons of war are the hottest fashion accessory in GOP campaign ads.

The message many Republicans receive is that violence is justified to save the United States from a leftist takeover. An audience member at a pro-Trump event spoke for many when he asked: “When do we get to use the guns?”

An American Enterprise Institute poll found that 39 percent of Republicans believe, “if elected leaders will not protect America, the people must do it themselves, even if it requires violent actions.” Another survey by the University of Chicago found that 21 million adults believe the “use of force is justified” to restore Trump to the presidency.

Of course, the vast majority of people who think that violence is justified won’t actually use it. But it doesn’t take many extremists to cause mayhem in a country awash in firearms. Terrorist groups such as the Baader-Meinhof gang and the Irish Republican Army were able to carry out attacks for decades even while having memberships ranging from a few hundred to a few thousand.

We are at the greatest peril since the early 1970s — when the threat emanated from the left — of a violent insurgency in America. Indeed, the scattered terrorist attacks we have seen in recent years might be the early stages of such an uprising. If we see a full-blown insurgency — something that becomes more likely if Trump runs and loses again in 2024 — it would bear roughly the same symbiotic relationship to the GOP that the IRA had to the Sinn Fein party: It would be the armed wing of a larger right-wing movement. Trump made the relationship explicit when he told the Proud Boys, an armed group that later took part in the Jan. 6 attack on Congress, to “stand back and stand by.”

Rep. Paul A. Gosar (R-Ariz.) has made himself the poster boy for Republican extremism. He spoke in February at a conference organized by a white-supremacist Holocaust denier. He has promoted conspiracy theories about Jan. 6, claiming that the FBI might have been responsible for the attack. He tweeted an animated video showing him killing Rep. Alexandria Ocasio-Cortez (D-N.Y.) and attacking President Biden. Last week, he joined other House Republicans in hero-worshiping Rittenhouse; at least three of them want the violent vigilante to intern for them.

Gosar’s video showing him killing a co-worker would have gotten him fired in nearly any other workplace in the United States. But only two House Republicans voted to censure him last week. Instead of expressing outrage over Gosar’s conduct, most Republicans expressed outrage that Democrats would dare to call him out.

Why do so many Republicans go along with extremism? Some, like Gosar, are zealots themselves. But many others are simply afraid of the crazies. Rep. Jason Crow (D-Colo.) said Republican colleagues told him they feared for their safety if they voted to impeach Trump in January. One of the pro-impeachment Republicans, Rep. Anthony Gonzalez (Ohio), is leaving Congress in part, he says, because of the danger to him and his family. Even the 13 House Republicans who recently voted for a bipartisan infrastructure bill have received death threats.

Republicans are complicit in fomenting violent extremism — and they have also become hostage to the extremists in their ranks. It’s an ugly situation familiar from other people’s civil wars, and it portends more grief and bloodshed for a country that has already seen far too much of both. It’s not too late to avert a wider insurgency, but it will require Republicans to dial down their violent and apocalyptic rhetoric — which they show no sign of doing.