President Trump has threatened to use the army to tackle the "violent mobs" who he says are disrupting peaceful protests.
He said if cities and states failed to control the protests and "defend their residents" he would deploy the army and "quickly solve the problem for them".
Protests over the death of George Floyd are entering their seventh day.
Mr Trump said "all Americans were rightly sickened and revolted by the brutal death of George Floyd" but said his memory must not be "drowned out by an angry mob".
In a speech in the White House gardens, the president said: "As we speak I am dispatching thousands and thousands of heavily armed soldiers, military personnel and law enforcement officers, to stop the rioting, looting and wanton destruction of property."
Shortly after he finished his speech, he travelled to a church close to the White House.
This church has been visited by every US President since it was built in 1816 and is considered an important historical site. On Sunday it had been set on fire during the protests.
However, on Monday afternoon many were upset and angered as the crowd who had been peacefully protesting outside the church had been pushed back and away using tear gas and rubber bullets to give President Trump access to the front of the church.
Using the army on US soil would be a big step - if President Trump wants to do this he must use a law called the 1807 Insurrection Act.
But it is very rare to use the military to manage protests as people have the right to do it peacefully, and using soldiers, rather than police officers, to manage the situation would be very unusual. If he goes ahead, it will be the first time the US army has been used in this way for 28 years.
The last time the military was called to stop protests was in 1992 after a group of police officers were found not guilty for assaulting an African-American man named Rodney King.
Mr Trump has been very critical of opposition politicians in areas where some violent protests have taken place and he has been accused of stirring up violence with the language that he has used.
Last week, President Trump shared a tweet which was hidden from view by Twitter moderators, as they said it encouraged violence. Users are not able to comment or 'like' the tweet.
George Floyd was an African-American man who died after being held in police custody on 25 May.
His death has led to large protests, some of them violent, in many of America's biggest cities.
The policemen who were involved with Mr Floyd have been sacked and one of them has been charged with murder.
What happened to him has again raised the issue of racism in American society and the unfair treatment that many African-American communities feel they face in the US, particularly when it comes to the police.
Many politicians opposed to Mr Trump have spoken out about his threat to use the army.
Joe Biden, who is likely to challenge Mr Trump for the job of president in November's elections said Mr Trump was "using the American military against the American people".
Letitia James, New York's Attorney General, said: "The president does not have the right to unilaterally deploy US military across American states."
She has threatened to sue President Trump in protest at his decision.