AMNA NAWAZ: For more on the questions surrounding Saturday's attack, let's turn now to Bill Gage, a Secret Service special agent for 12 years, including as a counterassault team leader.

He's currently executive protection director for the SafeHaven Security Group.

Bill, welcome to the "News Hour."

Thanks for joining us.

BILL GAGE, Former U.S.

Secret Service Agent: Hi.

Thanks for having me.

AMNA NAWAZ: So the attacker in this case did not make it into the ballroom.

No one was killed, thank goodness.

The White House has been saying, look, the security protocols worked.

The attorney general, acting attorney general, Todd Blanche said this was a massive security success story.

Do you see it that way?

BILL GAGE: I do see it that way.

Secret Service operates having sort of overlapping and concentric rings of security, sort of an inner perimeter, outer perimeter, middle perimeter.

And each of those perimeters are set up in a way that, if one of them sort of fails or is stretched, the overlapping one will sort of be able to stop an attacker.

And that's what happened here.

I think the acting attorney general has talked about how the attacker kind of breached.

I think he said some version of that, sort of breached the outer perimeter.

And so that's what happened here.

He was momentarily able to get through the magnetometer checkpoint by just sure speed before the agents working that main magnetometer checkpoint were able to engage him.

There also were agents stationed at the door and also on the inside of the event just inside the door.

So those were additional layers of security that he would have had to go through before sort of being able to fully carry out his attack.

So it did work here.

The Secret Service protective sort of model worked here.

But after each of these sort of incidents, the Secret Service studies political assassinations that happen all over the world and they use them to sort of refine and improve their own protective model.

I remember going as a young agent through training.

We studied these assassinations in depth.

And so what's going to happen here is the Secret Service is going to make changes to the protective model.

And, in fact, I think you're going to see some of those changes actually this week probably with the king of England visiting here.

There's going to be immediate impact to his security plan.

I think you're going to see those magnetometer checkpoints pushed out some and those checkpoints being staffed by additional agents, probably tactical teams.

So I think you're going to see an immediate impact.

AMNA NAWAZ: Well, let me ask you about this because I know you have been part of the preparations for these dinners in years past.

It's held at a working, functioning hotel, right?

It has been for 60 years.

There are other guests coming and going.

The fact that an armed assailant was able to check in with weapons and get as close as he did, even if he was stopped after that breach of the magnetometers there, what does that say to you?

Should there have been additional security measures or barriers in place here before the president of the United States was in there?

BILL GAGE: So, listen, that's a challenge for the Secret Service, right?

We're not a dictatorship.

We're not China or Russia, where Putin can go to a hotel and kick the guest out and shut the hotel completely down.

This event happens at a very public hotel in a major U.S.

city, right off of a very busy street.

And so it's very difficult for the service.

They have to strike a balance between getting a secure perimeter and securing the venue.

So you have to strike the balance between securing that venue, but also allowing the hotel to operate and not being overly burdensome on the hotel.

There are people there.

There are businesspeople, other travelers, tourists that are visiting that hotel at the moment.

They have nothing to do with the event.

And so the Secret Service has to strike a balance between not being overly intrusive to the day-to-day operations of the hotel, while also ensuring that they can have a secure venue.

So that's really part of the challenge.

And the service does it every day.

AMNA NAWAZ: Tell us about that balance and how it's struck, though, because our understanding is that this event reportedly was not given what is the highest level of security designation, a national special security event.

And yet you have the president, the vice president, the secretary of defense, senior Cabinet officials, members of Congress in the room.

Why doesn't it get that highest level security designation?

BILL GAGE: Yes, great question.

And so those National Special Security Events are called NSSEs, and those actually -- there's a whole procedure for an event to be designated an NSSE.

It has to be -- it's a joint agreement between Congress and the secretary of Department of Homeland Security.

So they sort of have to come together, reach an agreement.

It has to be designated an NSSE.

There's an entirely different budget procedure.

So it's not as simple as a president or somebody saying, hey, this event's going to be an NSSE.

There's been a procedure in place since September 11, since that part of the United States code set up the NSSEs.

And so, yes, was this a mistake probably that someone overlooked.

Most likely, yes, I think we can all agree that there should have been some more procedures in place.

One of the things that I talk about here is that the State of the Union, that happens every year.

We have to ensure the continuity of operations or the continuity of our government to make sure our government can function, we have a leader.

So the service, they operate that program for the designated survivor.

Why it wasn't done here, I don't know, but I think you're going to see moving forward you're going to see events like this that have all of the leadership and the members of the lines of succession in there.

There's going to be probably a designated survivor.

And one of the other things, let me just further the point here.

I think one of the things the service is going to improve on -- improve upon on their protective model here is going to be the evacuation of some of these other details for other Cabinet officials.

When you see some of the video footage, and I have seen it, where you have members of the government, very senior members, Kash Patel, the treasury secretary hiding under tables or motioning for their protective detail to come get them, and then you see RFK kind of stepping on people and being ushered out.

So that was a very chaotic moment for these other details of these other Cabinet officials.

So I think the Secret Service is going to improve that, where there's going to be some more procedures in place to evacuate some of these other Cabinet officials.

AMNA NAWAZ: So, if this dinner gets rescheduled, what are specific measures you would like to see in place?

BILL GAGE: The Secret Service is going to need to move those magnetometers further out from the entry doors, further out.

They're going to have to harden up those magnetometer checkpoints with additional agents and probably some tactical teams.

They're going to have to work on these evacuation plans if other members of the government are there.

And I think the Secret Service is going to probably, unfortunately, have to -- if it's at a hotel, they're going to have to start inconveniencing the hotel more than they already do.

Trump is the most threatened president in the history of the United States.

I mean, there's been three attempts now.

So I think the Secret Service has an incredible mission here.

It's a zero fail mission.

And they're going to have to improve, which I know they will.

They're going to study what happened on Saturday.

They're going to improve their protective model.

They're going to make immediate changes.

They probably already have.

So I think the magnetometers, pushing them out, hardening up the magnetometers, and also improving these evacuation plans I think are some immediate things that the Secret Service can do and what they will do for the next event if it happens.

AMNA NAWAZ: All right, that is Bill Gage, former Secret Service special agent now with the SafeHaven Security Group.

Bill, thank you so much for your time.

We really appreciate it.

BILL GAGE: Thanks for having me.