Police Chief Cathy L. Lanier (Bill O’Leary/The Washington Post)

Citing disappearing open-air drug markets and new ways narcotics are being sold, D.C. Police Chief Cathy L. Lanier says she wants her detectives to concentrate on suppliers and not street-corner busts that have long been a staple of policing across the country.

The strategy shift, outlined at a community meeting Thursday, will eliminate most of the plainclothes operations police have used for decades to target outdoor drug sales, magnets for drive-by shootings and other violence.

Coming at a tense moment in the nation’s relations between police and the public, it could also ease confrontations involving officers not immediately identifiable as law enforcement. It is an admission that some tactics — which were viewed by some critics as heavy-handed even when the crack epidemic sparked record numbers of homicides — no longer make sense amid a decline in fatal shootings and the availability of synthetic narcotics sold over the Internet, through social media and in convenience stores.

“Our main goal is the supply,” Lanier told about three dozen residents at the community forum in Northeast Washington. “We don’t want to focus police efforts on just people who are addicted. We want to be focusing on the people who are bringing the stuff in.” In an interview, she added: “Our criminal environment is changing rapidly. We have to keep up.”

The plan would eliminate District vice squads — each with about 20 detectives and supervisors — and shift higher-level investigations to the centralized Narcotics and Special Investigations Division. Police will continue undercover operations, but as much as possible, Lanier wants police to be identifiable when making arrests.

The changes are resulting in praise from experts pushing for innovation in policing, guarded optimism among activists who have complained about aggressive police tactics and skepticism from the head of the union representing the District’s rank-and-file officers.

Although D.C. police have escaped the controversies and tumult other cities have experienced after the deaths of black men at the hands of law enforcement — such as in Baltimore, Cleveland, New York and Ferguson, Mo. — critics have complained that in the District, plainclothes officers jump from unmarked cars to roust suspected people, innocent and not, on street corners. Lanier has said specialized “jump out” squads have not been used in some time. She has previously said that in some cases, officers are responding to 911 calls or searching for particular suspects. Residents may also see officers from other agencies, she has said.

Monica Hopkins-Maxwell, executive director of the Washington office of the American Civil Liberties Union — whose staff has said D.C. officers are too aggressive in poor, high-crime neighborhoods — called Lanier’s changes a “good first step.”

“It is a very clear message that the strategies employed by [D.C. police] have not been effective, whether it has to do with the changing nature of crime, of drugs or the community response,” Hopkins-Maxwell said.

But Delroy Burton, chairman of the union that represents the District’s officers, said there could be a negative effect on neighborhoods. The changes mean that police district commanders “won’t have as many options to deal with minor drug problems” that don’t merit attention from the larger squad focused on the city.

Lanier said she wants to focus on drugs that pose major public-safety threats.

Police say they believe that PCP, club drugs such as MDMA (also known as ecstasy or Molly) and other synthetic drugs are the latest problems and require new approaches. The Internet is used in the supply line for many of those drugs. Heroin also has caused concern because of a high number of overdoses nationwide.

Authorities in the Washington area have traced PCP from the West Coast, club drugs like MDMA to local bathtub labs and synthetic drugs from as far away as China, Lanier said. Police have been able to seize large quantities of synthetic drugs in recent years, including 137 kilos in 2013, 120 kilos in 2014 and, so far this year, 25 kilos.

Marijuana, although still illegal to sell, is legal to possess in the District and use in small quantities, and police have largely stopped targeting the drug.

Police say that in the early 2000s, they identified 210 open-air drug markets in the District. Today, few operate in the open, Lanier said. Homicides have also decreased. The District recorded annual killings in the 300s and 400s during the late 1980s and through much of the 1990s, when crack was rampant. Those numbers are now in the low 100s.

“The criminal enterprise has changed. The criminals have gone high-tech, so our methods have got to go high-tech, too,” Lanier said.

The chief has hinted at the department’s changes during community meetings and before the D.C. Council, and other cities have taken similar approaches. Among the first was High Point, N.C., a city of about 110,000 outside Greensboro, which created its Drug Market Initiative.

Police there identified drug markets and arrested the handful of dealers with the most significant records. They told others to change or face jail time and then started working with residents to address the smaller, quality-of-life crimes. “Like every other police department, we would do a zero-tolerance sting or a street sweep,” said Capt. Tim Ellenberger, who runs High Point’s major crimes division.

“While those operations seemed on the face of it productive, they clogged the justice system, felonized people not driving the violence and angered the people who lived there. . . . We weren’t making anything better.”

Now, Ellenberger said, “we target the people responsible for the violence surrounding a drug market. It’s fairer to the residents. It’s smarter policing.”

John DeCarlo, an associate professor at John Jay College of Criminal Justice in New York and a former police chief in Branford, Conn., said that “focused deterrence works better than a general war on drugs.”

The retired 34-year police veteran said “the whole face of drug markets has changed. . . . On the dark Web, you can buy and have delivered to your house just about any drug you can think of. It’s child’s play.”

Reducing confrontations between police and residents who often feel under siege will have added benefits, DeCarlo said.

Lanier has made no secret that the changes are, in part, to help improve relations with the community, saying she is “committed to a strategy that focuses on less crime and less arrests.”