The day after five Dallas police officers were killed in an ambush, Montrell Jackson, a black police officer in Baton Rouge, La., took to Facebook to voice his frustration.

“I’m tired physically and emotionally,” he wrote, questioning the “nasty hateful looks” he received as a police officer and the “threat” he felt when he was not in uniform. “When people you know begin to question your integrity you realize that they don’t really know you at all.”

But he was hopeful: “I’m working these streets so any protesters, officers, friends, family, or whoever, if you see me and need a hug or want to say a prayer. I got you.”

Less than two weeks later, he was dead, along with two other officers, killed by another gunman targeting police officers. In each of the attacks on officers, the assailant was black, seemingly intent on avenging the recent deaths of civilians killed by police officers in Baton Rouge and Falcon Heights, Minn.

Jackson’s haunting reflections before he died echo the particular strain of anguish facing black police officers around the country as the nation wrestles with the aftermath of killings involving the police.

The deaths, the ensuing protests and the fatal attacks on police officers in Dallas and Baton Rouge have intensified the internal tug of war that black police officers endure, the daily duality of being black and serving in blue.

Detective Derick Waller, a 21-year veteran of the New York Police Department who is black, said he worried the tensions would edge officers even deeper into danger.

“No officer leaves his house and says, ‘Man, I want to kill somebody today,’” Waller said.

Still, Waller said he sympathized with African-Americans who say they are wrongfully singled out by the police.

“There is something that’s rooted in America in the police department,” he said. “It’s just assumed that every black person that has a car with tint has a gun.” Being stopped by a police officer fills him with fear, Waller said. “When I get pulled over, I get scared. I turn my ignition off, and I put my hands out the window.”

The succession of high-profile killings of black men by the police in recent years — in Ferguson, Mo.; North Charleston, S.C.; Baltimore; New York City; and most recently in Baton Rouge and Falcon Heights — have touched off protests across the nation and given growing prominence to a movement, Black Lives Matter, dedicated to addressing inequities and discrimination in the criminal justice system.

The movement’s often boisterous denunciations of police violence have prompted a backlash from police unions, politicians and some rank-and-file officers, who accuse it of sowing hatred against men and women in uniform. Some have even blamed the movement for inspiring the gunmen in Dallas and Baton Rouge.

It is the same sentiment that slowed the movement’s campaign in New York City after two police officers were killed in an ambush in December 2014 by a mentally ill black man. The man, who killed himself shortly after killing the officers, had cited on social media the deaths of Eric Garner, the Staten Island man killed by the police in July 2014, and Michael Brown, the man killed by in Ferguson in August 2014.

Black police officers said that when the topic was race and policing, they often sidestepped talking in public, and even talking with their co-workers.

In downtown Cleveland, where Republican conventiongoers frequently cheered officers patrolling in groups on Monday, an eight-year veteran of the city’s transit police said the strain around race and policing had become so great, he had taken to avoiding the subject at work.

Standing near a group of activists protesting Donald Trump’s nomination in a public square, he recounted a story about once being late to a shift and showing up in his civilian clothes, a white T-shirt and jeans. When he got to the office, a fellow officer approached him and said, half-jokingly, that he thought the officer might be a robbery suspect. “As a police officer, it’s a culture that nobody wants to talk about,” he said. They don’t want to admit they might have singled someone out for how they look.”

At home, some family members and friends avoid certain subjects around him, just as he avoids some subjects with his fellow officers.

Talking to relatives can be agonizing.

Lt. Zsakhiem James, who has been a police officer in Camden, N.J., for 23 years, drove to Dallas with four other officers to pay their respects, only to return to the news of the Baton Rouge ambush.

He said his mother asked him on Monday, “How do you still do the job?” She was referring to his safety, but the inquiry was freighted with deeper questions. “How do you put the uniform on and still go out after seeing all the things you’ve seen as a black man and everything that’s going on in the world and still do your job, and do your job right?” James said.

He was bracing for similar questions at a family reunion. “I feel a sense of loss, but as a police officer, before I cast judgment, I wait for the full information to come out,” James said. “And they look at me and say, ‘Aren’t you outraged?’ And I say I’m outraged at the loss of a life; and what they don’t understand is that the loss of any life at the hands of a police officer reflects on all police officers.”

Just as Twitter has helped nurture and sustain the protest movement, many officers have taken to Facebook to voice their own sentiments on the criticism shaking their profession, if only to their family and friends.

In some cases, posts intended as private exchanges, like the one by Jackson, have been thrust into the public sphere as sympathetic friends seek to show the world just how misunderstood black officers feel and just how frustrated they are — with other police officers, and with some people in the black community.

After the death of Alton B. Sterling in Baton Rouge this month, Nakia Jones, a police officer in Warrensville Heights, a Cleveland suburb, denounced racism among some of her colleagues and tearfully begged black people to “put these guns down, because we’re killing each other.”

“If you are white and you’re working in a black community and you are racist, you need to be ashamed of yourself,” she said in a video that has been viewed nearly 8 million times.

In Kalamazoo, Mich., a city of 76,000 people that is about 20 percent African-American, Lt. Anthony Morgan said he had faced hard questions from the black men in his family about policing issues, while also counseling the officers he supervises, most of them white. “The truth hurts, and you have to be honest with both sides,” he said.

In recent days, there has also been a positive response from the community, with strangers offering meals and kind words on the street, Morgan said.

Kalvin Barrett, a police officer in Sun Prairie, Wis., a suburb of Madison that is about 6 percent black, said that residents there had largely been supportive but that he has had some difficult interactions over the years. In one case, as he was arresting a drunken driver who was African-American, the driver called him an Uncle Tom and told him he probably just wanted to harass people.

“I ran into that individual about three weeks later, and he apologized to me,” Barrett said. “That really showed me that people go through tough times in their life, and you can’t hold them accountable” for everything they say.

But many black officers are pained by the thought that people who look like them are scared of them or even hate them because of the uniform they wear.

A black officer in South Florida, who agreed to be interviewed only if he was identified by his nickname and middle name, Jay Stalien, said that when he came upon a motorist who had made an illegal turn recently and flipped on his lights, the driver initially refused to pull over. The motorist, a black woman, later explained that she was looking for a well-lit place to stop because she feared an encounter with the police.

“Before it was just criminals that didn’t like you,” said Stalien, who recently expressed his frustrations in a post on Facebook. “Now everybody believes we’re the bad guy. People who have never had a negative encounter with the police in their lives think they’re in danger when we pull them over. It’s disheartening.”

© 2016 The New York Times Company