US Attorney General William Barr is currently testifying before Congress regarding the decision to send federal agents to various cities in order to help gain control over protests and riots, the BBC reports.

Barr told Congress that rioters were committing "an assault on the government of the United States."

Attention is being focused on the city of Portland, Oregon, the scene of 61 consecutive nights of protests, sometimes violent, in the wake of the police killing of George Floyd in May.

House Judiciary Committee Chairman Jerrold Nadler (Dem) told Barr: "The president wants footage for his campaign ads and you appear to be serving it up to him as ordered ... Now you are projecting fear and violence nationwide in pursuit of obvious political objectives. Shame on you Mr Barr. Shame on you."

Republicans on the committee focused on the many violent acts that rioters have committed against police, and Barr told committee members that, "We are on the defence ... We are not out looking for trouble ... [we're not trying to] suppress demonstrators."