US President Donald Trump has announced that he will deploy the National Guard in Washington DC to respond to what he says is an increase in crime.

Trump announced on Monday that he issued an Executive Order declaring an emergency, describing crime in Washington as being "out of control."

He said Washington last year had one of the highest rates for robbery and murder among large US cities. He ordered that local police be put under federal control and directed the secretary of defense to deploy the local National Guard.

At a news conference on Monday, Trump said Washington police and federal authorities will be supported by 800 National Guard personnel. He added that even more will be deployed if necessary. He vowed to "quickly" clean up the city.

Washington Mayor Muriel Bowser countered Trump by saying the city is "not experiencing a crime spike." She said that in the past two years, violent crime has fallen to its lowest level in 30 years.

Trump deployed the California National Guard and the Marines to Los Angeles in June to respond to what he said was rioting and looting surrounding immigration raids. His move invited opposition from the city's mayor and the governor of the state.

Some observers see Trump's measures as having political implications as the mayors of both Los Angeles and Washington are Democrats.