I think @aygart's question is a good one. Mimah nafshach, if the concern people were armed was real, how did the SS let the president speak at the rally? And if it wasn't a real concern, that majorly tempers concerns about Trump's encouragement of violence.
Trump spoke in the Ellipse, across the street from the White House lawn. That area started filling up in the morning.
CHENEY: When a President speaks, the Secret Service typically requires those attending to pass through metal detectors known as magnetometers, or mags for short. The Select Committee has learned that people who willingly entered the enclosed area for President Trump's speech were screened so they could attend the rally at the Ellipse. They had weapons and other items that
were confiscated:
pepper spray, knives, brass knuckles, tasers, body armor, gas masks, batons, blunt weapons. So Trump was sent that info, that these are the kinds of weapons that people brought to the rally. But not everybody gave up their weapons. The report of the Glock and AR-15 were from
morning police reports of people outside the Ellipse (one on Constitution Ave, one at 14th and Independence). We can't tell from this if the police subsequently apprehended those people before the president spoke, or if the USSS considered them far enough away, but in any event, they weren't near the president.
The USSS
were concerned about the weapons on the streets of DC, and therefore didn't allow the president to walk to the Capitol as he wanted.
Trump knew that people had brought weapons, and that not all those weapons had been confiscated. And he encouraged these people to go to the Capitol and "fight like hell".