It was remarkable that the Republican presidential candidates’ debate this week, supposedly focused on keeping Americans safe, was devoid of questions and comments about the public health issue of gun violence.

Instead, the nine Republican rivals spent much of their time dwelling darkly on potential threats from Islamic State terrorists. And when they brought up the mass shooting in San Bernardino, Calif., this month, carried out by a couple found to be inspired by Islamic State violence, the discussion never veered to the easy gun access that enabled those killers — and many others — to commit swift and horrific slaughter of innocent people.

That would have complicated their pitch, and more important, would mean thinking about gun violence in ways that would displease the gun industry and its political lobby. Those forces demand unquestioning allegiance from politicians fearful for their careers — outspoken candidates who retreat into shameful timidity when serious ideas on gun safety are needed. Strangely, the debate moderators didn’t care to touch the gun issue either, thereby burying a public health challenge that is a lethal, daily threat.

It’s easier for these candidates to engage in eerie discussions of whether the next president should be free to bomb civilians in Syria or shoot down Russian bombers in a no-fly zone. They are experts at stoking fears about terrorism and great at wringing their hands about the unfounded bomb scare that shut down the Los Angeles school district on Tuesday, but actually facing up to gun violence — which kills more than 33,000 Americans a year — is beyond their capacity or courage. Far from offering any ideas, their statements on the campaign trail are a national embarrassment.