From ABC News Headquarters in New York City, this is GMA3.

Hello everyone. I'm Rhiannan Alley.

And I'm Rebecca Jarvis here with Stephanie Ramos, and we're so glad you can join us to kick off your week on this Monday.

We sure are. And coming up here on GMA3, Dr. Darian Sutton's here to talk about adult onset allergies. He'll break down why they happen and give us some warning signs.

And registered dietitian and nutritionist, Maya Feller, is here with some sneaky ways you can boost protein in your kids' favorite foods.

I pass some of those options on my way and they sounded sneaky and good to me. But we begin with the latest on the attempted

attack at the White House, correspondence dinner, and the heightened threat environment. Chief

investigative correspondent, Aaron Kuturski, is here with more on that. What do we know now, Aaron?

Well, we are learning that when a man charged at that Secret Service checkpoint at the Washington Hilton,

Rebecca, he exposed a security vulnerability.

This guy's going to be in court a little bit later on today. And authority said the suspect was a guest at the Hilton,

giving him access to what was otherwise supposed to be a secure hotel with unchecked baggage.

Very same thing happened in 2017 when a gunman loaded bags full of

weapons into Mandalay Bay in Las Vegas, then committed the deadliest mass shooting in U.S. history.

Now, in this case, sources sold ABC News. The suspect booked his room earlier this month,

boarded a train from Los Angeles to Washington, and the belief is he traveled with the weapons,

the shotgun, the handgun, the knives, all

suggesting this was no spur of the moment thing, but something thought about in advance.

The sources also told ABC News the suspect sent a message to his family just before rushing the

checkpoint describing himself as a friendly federal assassin.

Yeah, and as you point out, that is a long way to travel completely undetective.

What are we thinking in terms of motive at this point?

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