AILSA CHANG, HOST:

How could this have happened? That remains the largest question two days after this scene at the U.S. Capitol.

(SOUNDBITE OF RIOT AMBIENCE)

CHANG: That, of course, is the sound of a mob of President Trump supporters breaking through fencing and overwhelming the few officers that were there as they stormed the Capitol on Wednesday. Senator Chris Murphy of Connecticut is the top Democrat on the Senate subcommittee that funds the U.S. Capitol Police. He has vowed that there will be an investigation into Wednesday's security breach. Senator Murphy joins us now. Welcome.

CHRIS MURPHY: Thanks for having me.

CHANG: So I just want to start with, is it clear to you that whatever plans were in place to protect the U.S. Capitol on Wednesday, those plans were monumentally insufficient?

MURPHY: There was a failure at almost every level to protect the Capitol. You know, you didn't have to be on the dark web to know that something really terrible might happen on Wednesday. It was pretty clear that there were some in that group that, you know, were at least contemplating an attack on the Capitol. And the minute that President Trump, you know, announced his intention to speak to the group and send them on a march to the Capitol, you had to understand what the very specific risk might be.

And then I think there's also big questions about protocols that day, why there were so few officers inside the building once the breach was made and why the heck it took four hours for the U.S. military to come to our defense. Why do we spend $700 billion on the U.S. military if you cannot defend the United States Capitol when the No. 1, 2 and 3 people in the presidential line of succession are in the building?

CHANG: I want to talk about the relative ease with which these rioters were able to enter the building because, as you say, plenty was known about what Trump supporters were planning to do. Do you think lack of preparation was the only thing to blame?

MURPHY: I think that is probably the biggest problem here, that had they had 1,000 or 2,000 prepositioned National Guard troops at the Capitol, I don't know whether the breach would have occurred. And then there are some really difficult questions to ask that I don't have the answers to right now. Obviously, we equip these Capitol Police officers with weapons. And by and large, they chose not to fire those weapons. If you aren't prepared to use lethal force, then it's just about how many people they have versus how many people you have.

CHANG: Well, I'm getting at a more pointed question, and that is the appearance of complicity from some of these officers. There are videos and accounts of some officers standing by as rioters roamed the halls, some with weapons, vandalizing property. Should those officers lose their badges?

MURPHY: I don't know if we have enough evidence yet to understand whether there was widespread behavior like some of what we've seen in these videos. I think once the individuals were inside the buildings, some of them armed, we have to ask the question, what orders did those officers have? I think if there's one officer inside the building and 20, 30 or 40 protesters, you need to ask, you know, what that one officer has the capability to do. So I think one of the first things we need to understand is, what was the plan? What were the orders given to these officers? Why were so many of them standing by?

CHANG: Well, the overall response from law enforcement that day to these intruders did appear passive, even deferential in cases, compared to what we saw last summer during the racial justice protests in Washington, D.C. Most of this mob forced its way into the Capitol and then, as you say, were allowed to walk out. So I want to be direct about this. How much do you think the race of these rioters played into how they were treated on Wednesday?

MURPHY: I think there's no doubt that if these were Black Lives Matter protesters walking into that building, they would have been treated much more roughly. I, you know, asked the question of the chief, why weren't there more than 14 arrests? His answer was they couldn't walk and chew gum at the same time. They couldn't clear the building at the same time as make arrests. But, you know, frankly, municipal and Capitol Police have been pretty good in the past at making mass arrests at protests. They train in that. And so you have to believe that some of the reason that there were almost no arrests on site had to have to do with the composition of the protesters.

CHANG: But, Senator, do you feel that the failure to arrest more people on Wednesday is going to only fuel their return on Inauguration Day and potentially create much greater unrest?

MURPHY: I do. I mean, it's pretty hard to go track these folks down when they're dispersed all around the country. We have not seen enough high-profile arrests in the last 24 hours so as to create a disincentive for this to happen again. But, you know, let's be clear. Even if the Trump FBI is slow-walking this, when Joe Biden gets sworn into office, he is going to use every means at his disposal to try to find out who was in the Capitol and who was responsible for this. So these people are going to be held to account. Maybe it won't be during the Trump administration. It will certainly be afterwards.

CHANG: Democratic Senator Chris Murphy of Connecticut, thank you very much for joining us today.

MURPHY: Thanks. Transcript provided by NPR, Copyright NPR.