Dallas officials say he was the sole shooter who killed five police officers and wounded seven other people during a Black Lives Matter protest march Thursday night.
"He was very disappointed, very disappointed".
Johnson's time in the Army was marked by a sexual harassment accusation in May 2014 while in Afghanistan.
Republican presumptive presidential nominee Donald Trump, speaking at a campaign event on Monday, mentioned the events in Dallas and said it's "time for hostility against police and all law enforcement to end immediately". His stepmother Donna is white.
He said Johnson had scrawled the letters "RB" in his own blood on a wall before dying. In Oakland, protestors blocked a major highway for several hours in response to police fatally shooting two black men earlier last week.
Although similar devices have been used in police operations, none were used to injure or kill a suspect, and until recently, repurposed bomb-disposal robots have been limited to the military.
Police killed Alton Sterling in Baton Rouge, Louisiana, and Philando Castile in the Twin Cities suburb of Falcon Heights last week.
"I don't know what to say to anybody to make anything better", James Johnson said.
Brown said he has no regrets about the move, which relied on a $51,000 robot that the department bought in 2008. "I'd use any tool necessary to save officers lives". "Serve your communities", Chief Brown said during a Monday news conference.
The police chief also said the shooter had material for explosives and talked of using homemade bombs during the standoff. "This wasn't some novice", Brown said.
Investigators say they now believe that Johnson essentially shadowed the march, driving from street to street, and then parked the vehicle and went to higher ground where he could get a better vantage point on police. "We don't have any evidence of that".
A peaceful protest over the recent videotaped shootings of black men by.
Hundreds demonstrated in Chicago, clapping and banging drums, and shouting "No justice, no peace". Some passing cars honked in support.
Three countries - the United Arab Emirates, Bahrain and the Bahamas - have warned their citizens to remain on guard when visiting U.S. cities where protests occur. In 2010, just weeks after he assumed the role of police chief in Dallas, Brown's mentally ill son shot and killed a police officer and another man, before being fatally shot.
Rick Briscoe, legislative director of the gun rights group Open Carry Texas, said Mr Brown was "simply mistaken" in regarding armed civilians as a problem. "We're asking cops to do too much in this country, we are, we're just asking us to do too much, every societal failure, we put it off on the cops to solve, not enough mental health funding, let the cop handle it, not enough drug addiction funding, let's give it to the cops".
A makeshift memorial at Dallas Police Headquarters after multiple police shootings.
A candlelight vigil is due to be held at 8pm on Monday in Dallas City Hall plaza.
After refusing to speak to the media, the family reached out personally to TheBlaze's Lawrence Jones after seeing him on television.