Responding toclashes between protesters and police in Minneapolis following the deathof George Floyd, President Trump took to Twitter to denounce demonstrators and wrote "when the looting starts, the shooting starts." That phrase goes back to the Civil Rights Era, known to have been invoked in the 1960s by a white police chief cracking down on civil rights protests and a segregationist politician.

Twitter took an unprecedented step on Friday in limiting the public's ability to view the president's tweet threatening shooting, saying it "violated the Twitter Rules about glorifying violence." The tweet is hidden unless a user clicks to display it, and users cannot like or reply to it.

The phrase "when the looting starts, the shooting starts" was used in 1967 by former Miami police chief Walter Headley during hearings about crime in the city, invoking angry reactions from civil rights leaders according to a news report at the time.

"He had a long history of bigotry against the black community," said Professor Clarence Lusane of Howard University.

"The NAACP and other black organizations had for years complained about the treatment of the black community by Miami police. At this hearing, in discussing how he would deal with what he called crime and thugs and threats by young black people, he issued this statement that the reason Miami had not had any riots up to that point, was because of the message he had sent out that 'when the looting starts, the shooting starts,'" Lusane explained.

Headley was head of the police force for twenty years and referred to his "get tough" policy on crime during a 1967 news conference as a war on "young hoodlums, from 15 to 21, who have taken advantage of the civil rights campaign... We don't mind being accused of police brutality."

According to Lusane, Headley himself may have borrowed the phrase from Eugene "Bull" Connor, who had been the notorious public safety commissioner in Birmingham, Ala., a segregationist who directed the use of police dogs and fire hoses against black demonstrators.

The late 1960s saw major riots and uprisings in cities like Detroit in response to police action against the black community.

Headley's use of the phrase is thought to have contributed to intensified race riots, including one of the most serious riots in Miami in 1980, when a black man, Arthur McDuffie, was beaten into a coma by up to a dozen white Dade County police officers after he ran a red light on his motorcycle. He later died from his injuries.

The phrase was also used in 1968 by segregationist presidential candidate George Wallace.

It's unclear whether Trump is aware of the phrase's history, and he did not explicitly invoke the historical context in his tweets.

He's also expressed sympathy over Floyd's death while in police custody. On May 27, Trump tweeted that the FBI and Department of Justice are "well into an investigation as to the very sad and tragic death in Minnesota of George Floyd." The president also said he asked for the investigation to be expedited.

Regardless of Trump's intended meaning in his comments about "looting" and "shooting," Lucane says the message sent is not one of reconciliation and healing.

"So often Trump has engaged in dog whistles," Lucane says. "But he also engages in blaring trumpets. And this is a pretty clear and very loud message that the response should not be let's try to address the justice issues that are involved here but let's be hard-line."

Copyright 2020 NPR. To see more, visit https://www.npr.org.