Pentagon officials say the National Guard troops will not perform law enforcement tasks, but will help support federal agents with logistics and transportation. Even critics of Mr. Trump’s decision to deploy the troops say it could allow overworked police officers to focus on major issues, including drugs and homicide.

Mr. Trump posted on social media last weekend that “The Homeless have to move out, IMMEDIATELY.” It is unclear what role, if any, the troops might have in clearing homeless encampments in the city.