U.S. Secretary of Defense Mark Esper has publicly expressed opposition to President Donald Trump's threat to use active duty troops to quell protests flaring up across the country following the death of a black man in police custody.

Breaking away from the commander in chief, Esper said in a news conference at the Pentagon on Wednesday that the military should not be sent to control the protests in American cities, at least for now. 

[Sound bite: US Secretary of Defense Mark Esper]
"The option to use active duty forces in a law enforcement role should only be used as a matter of last resort and only in the most urgent and dire of situations. We are not in one of those situations now. I do not support invoking the Insurrection Act."

Trump earlier threatened to invoke the 1807 Insurrection Act that would allow him to deploy troops to city streets against the wishes of state and city authorities.

Esper has been supportive of Trump and avoided contradicting him until now.

White House Press Secretary Kayleigh McEnany said the president has the sole authority to invoke the Insurrection Act.