Will police shootings of African-American men ever end?

Will it ever end? The shocking sequence of police shootings of African-American men has now claimed two more lives.

Keith Scott was killed in Charlotte, North Carolina, yesterday afternoon. Police say he was spotted with a weapon; his family say it was a book. The undercover officers were trying to arrest a different man.

On Friday night, in Oklahoma, a white policewoman shot dead another African American, Terence Crutcher, even though video shows - though inconclusively at the critical moment - that his hands were raised. He was unarmed, but that didn't save him.

It has raised racial and political tensions once more. Both presidential candidates have addressed the issue today via Twitter.

This is an issue that is likely to continue to feature on the campaign trail. But, more importantly, it deepen the suspicion and distrust already felt by minority communities towards law enforcement.

The long, hot American summer of racial turmoil is not yet over. Black Americans feel targeted and vulnerable. The police are under greater scrutiny than ever before. Officers face a clear test of their ability to show restraint. They are failing it.