President Donald Trump promised a forceful response to violent protests across the United States and threatened to deploy U.S. military forces if cities and states fail to contain unruly demonstrations touched off by the death of a black man in police custody.

During hastily arranged remarks Monday evening, Trump pledged to do everything he could to preserve order, including in Washington, where vandalism, looting and fires overshadowed three days of peaceful protests over the killing of George Floyd in Minneapolis last week.

"I am mobilizing all available federal resources — civilian and military — to stop the rioting and looting, to end the destruction and arson, and to protect the rights of law abiding Americans,” Trump said from the Rose Garden of the White House.