"Just the beginning": Pentagon sending 1,500 troops to U.S.-Mexico border

Driving the news: Acting Defense Secretary Robert Salesses said in a statement Wednesday that he's carrying out a series of actions to gain "complete operational control of the southern border."

• The Department of Defense will send an additional 1,500 people, along with helicopters and intelligence analysts "to support increased detection and monitoring efforts," Salesses said.
• There are already about 2,500 U.S. National Guard and Reserve forces there.

Zoom in: The Pentagon will also provide military aircraft to support the Department of Homeland Security's deportation flights of more than 5,000 undocumented immigrants from the areas of San Diego, California; and El Paso, Texas.

• The DOD will also start helping with the construction of temporary and permanent physical barriers at the border, aimed at curtailing illegal border crossings and trafficking.

What they're saying: "This is just the beginning," Salesses said.

• "President Trump directed action from the Department of Defense on securing our nation's borders and made clear he expects immediate results. That is exactly what our military is doing under his leadership."

The other side: Civil liberties groups promised to take legal action against any misuse of military on civilian populations.

• The American Civil Liberties Union (ACLU) tells Axios they are gathering information and will look at taking action.

Go deeper: Trump's orders unleash sweeping limits on immigration, asylum

Editor's note: Russell Contreras contributed reporting.