Those domestic extremist groups include anarchists, white supremacists and far-left extremists, some of whom have overlapping affiliations.

An announcement by the Justice Department on Sunday to use Joint Terrorism Task Forces around the country to investigate some of the violence in major cities singles out leftist Antifa activity, though US law enforcement officials say there are groups from both the extremist left and right involved in the riots and attacks on police.

Trump's and Barr's focus on left-leaning groups also stands in contrast with repeated warnings in recent years from US law enforcement that the rise of white supremacist groups has become the biggest domestic terrorism challenge.

Despite threats by the President to designate various groups as terrorists, the closest the Trump administration has come is, in recent weeks, the State Department's designation of a white supremacist group called Russian Imperial Movement, which is a foreign group but has some domestic US supporters, as a specially designated global terrorist group.