ARI SHAPIRO, HOST:

Are American police too afraid of the public? That's a sensitive question, especially after five officers were gunned down in Dallas last week. Many reformers say it has to be asked. NPR's Martin Kaste reports now on the growing debate inside the world of policing over whether cops are being taught to pull the trigger too fast.

MARTIN KASTE, BYLINE: When you listen to the protesters, the message is clear. They think police are too quick to pull the trigger when faced with potential danger. The thing is it's really hard to tell whether this is something that's changing. The stats on police use of force in this country are just too unreliable to say anything for certain. Still, Peter Kraska is one person who does think that police have become quicker to use force.

PETER KRASKA: From everything I can tell, even though amazingly we don't have good statistics on lethality by police, the problem has certainly gotten worse.

KASTE: Kraska is a professor who's made a career out of studying what he calls police militarization. He says this in part because of what we've been seeing in the videos lately, images of police shooting people who aren't clearly armed or who have made a false move. But he also points to something else.

KRASKA: One of the cultural changes that has gone along with what we call the militarization of policing is a type of training that specifically comes from military-trained people that emphasizes that the police need to be - they need to have a warrior mindset.

KASTE: He's thinking about certain training companies which over the past couple of decades have become very influential in the police world. He says what he doesn't like about them is the way they rely on videos of bad outcomes - police that are ambushed or rushed by suspects often with fatal results. One of the companies he has in mind is called Calibre Press.

Earlier this week, Calibre was giving a leadership class to officers from around St. Paul, Minn. The class is taught by the company's owner Jim Glennon. He's a former cop from Illinois who owns the company. He says during the session that just now wrapped up, he and these local cops talked about the public outrage over the death of Philando Castile, the man shot by a local officer last week.

JIM GLENNON: The main thing to think of it is this - is that the information is not out so why is everybody who doesn't know anything offering opinions outside of their field of expertise?

KASTE: Calibre is a major player in the world of police training. Glennon figures his company trained 20,000 people last year. The company's students include Officer Jeronimo Yanez, the officer who shot Castile. Glennon shows a sample of the kind of videos that he uses in his class.

GLENNON: Watch how fast this guy moves.

(SOUNDBITE OF ARCHIVED RECORDING)

UNIDENTIFIED OFFICER: You're going - you know what? Turn...

UNIDENTIFIED MAN: No, no, no, no. I don't want to...

UNIDENTIFIED OFFICER: Put your hands on the hood.

(SOUNDBITE OF GUNSHOTS)

KASTE: Glennon is unapologetic about using videos like this, and he dismisses the criticism of people like Kraska.

GLENNON: Here's what bothers me about, oh, we'll never show these videos because then we won't have aggressive cops. No, you'll have dead ones.

KASTE: He says his courses are all about balance. He wants police to watch these videos, discuss them and learn from them. And he points out that his company also teaches plenty of classes about de-escalation and bias. And he has no patience for the critics who say police training has become too militaristic.

GLENNON: The line out there by politicians and even some chiefs of police in this country who should know better are saying we train too much like warriors. When in fact, if we train more with stress, stress-induced training, we would actually shoot less.

KASTE: It is true that police train a lot less than most people assume. For instance, here in Minnesota, the training requirement is only 16 hours per year, and most of those hours are not spent in simulators or active scenarios, the kind of training that can teach cops how to keep their focus when the adrenaline starts pumping. That kind of training is expensive, especially for smaller departments.

So companies like Calibre fill the niche, and it's retired cops who do much of the training, whether with the companies or at the public institutions that teach aspiring police. James Densley is a criminologist at one such college in Minnesota, and he says the identity of these trainers can have an effect.

JAMES DENSLEY: Now, there's nothing wrong with having police officers training police officers. I mean, in many ways, intuitively it makes sense. But I think one of the downsides of it is it also perpetuates a sort of mindset that maybe those police officers who are now instructing had learned when they went through the system, and then they're just sort of handing it down to future generations.

KASTE: The mindset that he worries about is a sense of us versus them, one which regards the public as more dangerous than it really is. But that's a contentious opinion to hold right now, especially inside this world of police training. By saying things like this for the past few days Densley has stirred up some bitter responses from police and trainers. They accuse the academics and the reformers of telling cops that they should hesitate too long in the face of danger at the cost of their own safety. Martin Kaste, NPR News, St. Paul.