Trump had taken heat from Democrats and Republicans alike for his response to Saturday's violence in Charlottesville, Virginia.
A woman was killed and 19 others injured when a suspected Nazi sympathizer plowed his car into a crowd of anti-racism protesters after a violent rally by neo-Nazis and white supremacists over the removal of a Confederate statue.
After meeting with Attorney General Jeff Sessions and new FBI Director Christopher Wray, Trump got tough.
"Those who spread violence in the name of bigotry strike at the very core of America," Trump said in nationally televised remarks from the White House, where he travelled early Monday to meet with his top law enforcement aides.
"Racism is evil. And those who cause violence in its name are criminals and thugs, including the KKK, neo-Nazis, white supremacists and other hate groups that are repugnant to everything we hold dear as Americans," he said.
"To anyone who acted criminally in this weekend's racist violence, you will be held fully accountable. Justice will be delivered."
In an appearance Saturday at his golf resort in New Jersey, Trump had faulted "many sides" for the violence but made no specific mention of the white extremists involved in the melee, some of whom wore Trump hats and T-shirts.
Earlier Monday, Sessions said in an interview on ABC's "Good Morning America" program that the car attack "does meet the definition of domestic terrorism."
"You can be sure we will charge and advance the investigation towards the most serious charges that can be brought because this is unequivocally an unacceptable, evil attack," he told ABC.
White nationalist demonstrators clash with a counter demonstrator at the entrance to Lee Park in Charlottesville, Va., Saturday, Aug. 12, 2017. Source: AAP
The Justice Department has launched a civil rights inquiry in connection with the incident, and the driver, a 20-year-old Ohio man who was said to have had a history of neo-Nazi beliefs, has been charged with second-degree murder.
On Monday, a judge denied bail for the suspected attacker, James Fields.
Backlash mounts
After a weekend of criticism of Trump from both sides of the political aisle, a prominent African-American businessman quit a presidential advisory body Monday to protest what he deemed an insufficient response.
"Our country's strength stems from its diversity and the contributions made by men and women of different faiths, races, sexual orientations and political beliefs," Ken Frazier, chief executive of Merck Pharmaceutical, said in announcing his resignation from Trump's American Manufacturing Council.
"America's leaders must honor our fundamental values by clearly rejecting expressions of hatred, bigotry and group supremacy, which run counter to the American ideal that all people are created equal," Frazier said.
"As CEO of Merck and as a matter of personal conscience, I feel a responsibility to take a stand against intolerance and extremism."
Trump was quick to lash out at Frazier's move.
"Now that Ken Frazier of Merck Pharma has resigned from President's Manufacturing Council, he will have more time to LOWER RIPOFF DRUG PRICES!" the president said on Twitter.
'Dangerous fringe groups'
On Sunday, the White House and top administration officials strove to defend the president.
"The president said very strongly in his statement yesterday that he condemns all forms of violence, bigotry and hatred," the White House said in a statement.
"Of course that includes white supremacists, KKK, neo-Nazi and all extremist groups."
On a visit to Colombia, Vice President Mike Pence said: "These dangerous fringe groups have no place in American public life and in the American debate, and we condemn them in the strongest possible terms."
Pence also defended Trump, saying the president "clearly and unambiguously condemned the bigotry, violence and hatred" on display in Charlottesville.
The Charlottesville mayor, Michael Signer, a Democrat, however laid much of the blame for the violence directly at the president's feet, saying on CBS that Trump had created an atmosphere of "coarseness, cynicism (and) bullying."
Of the 19 people injured on Saturday, 10 remained hospitalized in good condition and nine had been released, the University of Virginia Health System said.
Two state police officers involved in the law enforcement deployment for the rally also died Saturday in a helicopter crash.
Trump faced criticism during last year's presidential campaign for failing to quickly reject a vow of support from a former Ku Klux Klan leader, David Duke, though he eventually did so. Duke attended Saturday's rally.
The president has long had a following among white supremacist groups attracted to his nationalist rhetoric on immigration and other hot-button issues.
