This video shows a scenario-based training exercise conducted by the New York City Police Dept. at the New York Police Academy in July 2016. In the video, police officers respond to a call about a man who is agitated, suicidal and holding a knife. (Police Executive Research Forum, New York City Police Dept.)

A new training program to teach street officers tactics to defuse tense encounters with people who aren’t wielding guns is being embraced by police chiefs in many of America’s biggest cities as a way to prevent hundreds of fatal shootings each year.

Even with the national focus on police-involved shootings, from dramatic videos to community protests to officer prosecutions, the number of fatal police shootings in the United States this year is on pace to match last year’s total of 991. But in about 40 percent of cases, the subject does not have a gun, and many police officials think that reducing the intensity of such encounters, establishing more distance between officer and subject, and simply talking to the person can result in no shots being fired and less trauma on all sides.

Although some departments have adopted similar programs, this effort, being rolled out Sunday at a national police convention, would implement de-escalation training on a much broader scale, potentially reaching hundreds of thousands of officers across the country.

“These shootings by and large are not the officers’ fault,” said Chuck Wexler, executive director of the Police Executive Research Forum (PERF), the Washington think tank pushing the new program. “They’re doing what they’re trained to do. We have to change that training. We have to give them more tools to slow things down. It’s a change in culture, a different way of thinking.”

And so at the largest national police event of the year, the annual convention of the International Association of Chiefs of Police, in San Diego, Wexler is staging a town hall Sunday where he expects 500 big-city police chiefs to express their support for retraining officers to “de-escalate” and take a “tactical pause” when encountering subjects who do not present an immediate threat. Police departments in New York, Chicago and Baltimore already have endorsed PERF’s “30 Guiding Principles on Use of Force,” which call for officers to respect the “sanctity of life” for everyone, not just the police, in a critical incident.

This video shows a scenario-based training exercise conducted by the New York City Police Dept. at the New York Police Academy in July 2016. In the video, police officers respond to a call from a woman whose "son" is acting suicidal and holding a baseball bat. (Police Executive Research Forum, New York City Police Dept.)

But Wexler’s proposal remains hugely controversial in U.S. law enforcement, including with the president of the IACP, Chief Terry Cunningham, of Wellesley, Mass., whose organization comprises 18,000 police chiefs nationwide, mostly from small departments. After Wexler proposed the theory of the “PERF 30” in January, the IACP joined forces with the Fraternal Order of Police union to denounce the concept, and now that retraining programs are in place, those denunciations remain in full effect.

“An officer can only de-escalate a situation if the person they’re dealing with is willing to de-escalate,” Cunningham said.

Cunningham said he wasn’t certain that the number of police shootings in the United States was a problem, in the context of the millions of police contacts and hundreds of clearly justifiable shootings each year. “We just don’t know” whether the number of officer-involved shootings is excessive, Cunningham said. “We need to be careful because we don’t have good information, and shame on us for that.”

On Thursday, the Justice Department announced plans to begin collecting use-of-force data by police in a pilot program beginning next year.

In the absence of any government database of police shootings, The Washington Post launched one in 2015, as did the Guardian newspaper. Of the 991 fatal police shootings in 2015, 782 involved deadly weapons, mostly guns but many of them knives, while 93 people were unarmed and 27 were “unknown.” Of the 754 shootings by police recorded by The Post this year, 414 involved subjects with guns and 134 with knives; 43 subjects were unarmed, and 49 are listed as “unknown.”

This video shows a scenario-based training exercise conducted by the New York City Police Dept. at the New York Police Academy in July 2016. In the video, police officers respond to a woman who shows a calm demeanor, but is suicidal and is holding a knife. (Police Executive Research Forum, New York City Police Dept.)

Jim Pasco, executive director of the Fraternal Order of Police, said officers have always been taught de-escalation but cautioned against an overemphasis on those tactics. “A police officer has to contemplate all of the options available to him or her in a nanosecond and make the snap judgment,” he said. “If somebody’s coming at you with a machete, how far can you back up and how quickly can you do it?”

PERF officials, whose membership includes nearly every police department serving a local population of more than 50,000, and police chiefs who endorse the new training say it is designed to keep officers safe, as well as the individuals they encounter. The approach starts with getting as much information about the subject of the call as possible from dispatchers and witnesses.

Is the person thought to be mentally ill? Wexler noted that “mentally ill people often don’t comply with orders” because they aren’t processing them clearly. Is someone wanting to commit “suicide by cop? That happens a lot,” Wexler said.

Officers approaching a scene should ask, “How do you slow it down?” said Tom Wilson, a former Anne Arundel County officer now working with PERF. “You don’t see SWAT teams shoot many people, they slow it down, they take positions,” using distance and cover to provide safety for the officer. The new training teaches officers not to shout the same order repeatedly but start a conversation to lower the temperature on both sides. Officers who have taken the pilot training said it gave them practical skills they could use immediately, Wilson said.

“We’ve created a culture in policing where officers believe repositioning is retreating,” said Camden County, N.J., Police Chief J. Scott Thomson, PERF’s board president. “And that we need to resolve situations as quickly as possible. And sometimes that may be the approach. But if we take a more deliberate approach, particularly when individuals don’t have firearms, we’re finding there are less incidents of use of deadly force.”

Thomson pointed to a recent incident in Camden in which a man with a knife menaced people in a restaurant, then walked into the street and began swinging the knife at others. Officers walked alongside the man for blocks, waiting for the right moment to wrap him up and disarm him.

“I can unequivocally say,” Thomson said, “six months before our training, we would’ve shot and killed that guy. It would have been a justifiable use of deadly force, but there was another way to handle it.” Since Camden began a “Guardian Culture Program” in July 2015, its officers have responded to more than 2,400 calls for armed persons, made 370 arrests and had only one officer-involved shooting, which Thomson said occurred during an ambush. He said excessive-force complaints against police dropped 42 percent.

In Palm Beach County, Fla., sheriff’s deputies were involved in nine shootings per year between 2012 and 2014. By focusing on “slowing things down” and the “pre-event phase of calls,” Capt. John L. Prieschl said, “we were able to reach a positive result a lot more often.” Last year, Palm Beach deputies shot only three people.

“Rushing into scenes to save the day” on every call, Prieschl said, “just wasn’t working for us. We needed to lose that cape and think about the basics, creating time and distance between us and the people we’re dealing with. When people call 911, they want you there right now. But we know if we can take a couple extra minutes, gather our resources, time is on our side.”

New York City’s SWAT team, its Emergency Services Unit, is widely cited as a model in calming tense situations and passing its training on to the city’s thousands of patrol officers. Between training and modified policies over the years, New York police went from shooting 994 people in 1972 to 79 people in 2014. The unit’s trainers helped PERF create its training.

“It saves lives,” said Chief Barry M. Barnard of Prince William County, Va., who has appointed a captain at his county’s police academy to instill the “PERF 30.”

Barnard was sensitive to claims that de-escalation can put officers at risk. A rookie Prince William officer, Ashley Guindon, was shot and killed in an ambush earlier this year. “There’s no way we can eliminate risk,” Barnard said. “But you can deploy strategies and training that will help reduce the risk.”

Some police experts have pushed back hard, saying that officer safety is paramount. “PERF piled on to the false media narrative that the police are the problem,” said retired Los Angeles police Capt. Greg Meyer. He said police shootings have declined sharply in Los Angeles in the last 20 years, though there is no national data over that time. “You’re seeing case after case, because of all the criticisms in the post-Ferguson era, where you see an officer back up and get killed or hurt that they would not have before.”

In Police magazine, Meyer wrote: “Force should be used sparingly, but when it comes it must be used effectively.”

PERF’s Wilson said, “This is all about prevention. Why aren’t shootings going down? There are ways to do it, starting with ‘Everyone goes home,’ not just the officer. If you’re not saying that, how are you changing policing?

Cunningham said “one of our issues with the PERF 30 is that it kind of implicitly validated the criticisms of our profession, without challenging the premise. Are there things that need to be changed? We should look at it, but I’m not sure.”

He said he’ll be there when Wexler unveils the de-escalation training at the IACP convention Sunday.