“A viscous, calculated and despicable attack on law enforcement.”

That’s how President Obama described the ambush of police by at least one sniper in Dallas. The officers were doing their jobs, enabling and protecting a group of people peacefully exercising their First Amendment rights to protest the latest killings of black men at the hands of police officers under questionable circumstances.

37-year old Alton Sterling was shot several times in the chest as he was pinned by two white police officers on Tuesday night — graphically chronicled on video from several angles

Wednesday, 32-year old Philando Castille was shot in his car after being stopped by police for a broken tail light in Falcon Heights, Minnesota. His girlfriend broadcast the aftermath live on Facebook, demonstrating an out-of-body composure while interacting with the officer who still had his gun drawn. Her four-year old daughter was in the backseat.

Also caught on video was 25-year old Micah Xavier Johnson, the sniper in Dallas. Before he was killed in a standoff with police, Johnson said he was upset with the police shootings and wanted to kill white people.

Dallas was already infamous from the assassination of President John F. Kennedy in 1963. But, according to the Washington Post, Dallas is progressively implementing police reform.

No doubt Black Lives Matter will again intersect with the Thin Blue Line this summer. Cooler heads must prevail.