“Bring the war home.”

That’s what protesters at the University of Wisconsin chanted in early 1970, denouncing defense-related research at the school during the Vietnam War. Later that summer, four men brought the war to campus. They set off a bomb at the Army Mathematics Research Center, killing a physics graduate student and injuring three others.

Critics were quick to blame the entire antiwar movement. But the attack also triggered sober reflection among the protesters, who asked themselves whether their increasingly aggressive language had encouraged it.

That’s precisely the kind of honest, good-faith reckoning that’s been missing among most Republicans in recent days. Last Friday, police said that a Florida supporter of President Donald Trump, Cesar Sayoc, was responsible for sending explosive packages to Barack Obama, Hillary Clinton, and several other prominent Democrats. Then, on Saturday, 11 people at a Pittsburgh synagogue were murdered by alleged gunman Robert Bowers, who reportedly didn’t vote for Trump but had posted diatribes echoing the president’s overheated rhetoric about the caravan of migrants from Central America.

White House officials responded defensively after both attacks, denying that Trump’s language might have helped provoke them. “The president is certainly not responsible for sending suspicious packages to someone, no more than Bernie Sanders was responsible for a supporter of his shooting up a Republican baseball field practice last year,” White House Press Secretary Sarah Huckabee Sanders said, referring to the attack that critically injured Republican Congressman Steve Scalise last year.