DALLAS • US President Barack Obama said protests against police violence in many cities over the weekend are "legitimate" but attacks on law enforcement officers undermine public support for the Black Lives Matter movement.
"Any violence directed at police officers is a reprehensible crime," Mr Obama told reporters yesterday in Madrid at a joint press conference with Spain's acting Prime Minister Mariano Rajoy.
Demonstrators have taken to the streets to protest against the most recent deaths of black men at the hands of police.
A peaceful protest last Thursday in Dallas erupted into gunfire when a black man, 25-year-old army veteran Micah Johnson, shot 12 police officers, killing five of them, in what he termed payback for earlier police actions.
Johnson had been practising detonating bombs and planned some kind of major attack even before the sniper-style assault, the city's police chief said yesterday.
Releasing chilling new details of the attack, police chief David Brown said Johnson taunted police as he negotiated with them during an hours-long stand-off - "playing games, laughing at us, singing" - asking how many policemen he had killed and saying that he wanted to take out more.
At one point, Johnson, apparently wounded, wrote the letters "rb" in his own blood on a wall at the community college where he was holed up during the shooting last Thursday. Mr Brown said it was not clear what those letters meant.
Protests against the killings of black people continued over the weekend, and police arrested several hundred demonstrators last Saturday in Baton Rouge, Louisiana, St Paul, Minnesota and Chicago.
Mr Obama said protests were part of the long-standing tradition of free speech and the ability to demonstrate in the United States.
He was speaking a day after saying, at a press conference in Poland, that the nation was not returning to the "enormous polarisation" of the 1960s.
Other social issues, including women's suffrage, the abortion-rights debate and the civil rights movement, have had moments of incivility, the President said.
"In a movement like Black Lives Matter, there's always going to be some folk who say things that are stupid or imprudent or are harsh," Mr Obama said.
"I don't think that we can hold well-meaning activists who are doing the right thing, peacefully protesting, responsible for everything that is uttered at a protest."
He derided those who, in raising the issue of fairness in the criminal justice system, attack police officers verbally, or worse.
He said they were "doing a disservice to the cause" with heated rhetoric.
Police believe that Johnson had been planning attacks long beforehand, and that the shooting deaths of two black men by police in Louisiana and Minnesota last week were a trigger that prompted him to act, Mr Brown told CNN.
A search of Johnson's Dallas-area home after he was killed by police turned up bomb-making materials and a manual in which he wrote about military tactics.
Investigators believe that "based on evidence of bomb-making materials and a journal, that the suspect had been practising explosive detonations and that the materials were such that it was large enough to have devastating effects throughout our city and our north Texas area", Mr Brown said.
Johnson was a private in the army reserve and had served in Afghanistan. He knew the route of the Dallas march, and his military training apparently benefited him during the shooting, Mr Brown said.
BLOOMBERG, REUTERS, AGENCE FRANCE-PRESSE