Editors at National Review Online explain why they believe the head of the Secret Service must step down.

The U.S. Secret Service failed. That Donald Trump is alive today is only a result of sheer luck — a bullet that missed by less than an inch, a head tilt at the right split second. But make no mistake, the fact that an aspiring assassin was able to get to an elevated position within an easy shot of the former president and leading candidate to be the next president is a stunning failure of an agency whose primary mission is to protect the president.

Let us also not forget that in addition to a bullet grazing Trump’s ear, there were multiple casualties — Corey Comperatore, a firefighter who died heroically shielding his family from bullets, and two others who were seriously injured.

In the aftermath of the shocking event on Saturday, many questions have been raised about the response. Why didn’t the counter-sniper team take out the shooter before he fired a shot? Why didn’t they respond more quickly as spectators frantically drew police attention to the suspicious man crawling on the roof? Why did they let Trump continue speaking once this threat was identified? Why didn’t they whisk him away sooner in case there was a second assassin?

These are all fair questions, but each one of them can be answered by some variation of explaining a breakdown in communication or imperfect responses in real time. The one question that was most perplexing from the day of the shooting was, how did the Secret Service allow a would-be assassin to get so close to the president, just 150 yards away — a shot that wouldn’t be too difficult for anybody with basic training in looking through the scope of a rifle and pulling a trigger? Why wasn’t somebody posted on the roof when that could have been arranged in advance?