At least 800 troops to be sent to US-Mexico border

Defence Secretary Jim Mattis is set to sign an order sending at least 800 troops to the US-Mexico border, officials said.

Mr Mattis is responding to a request from President Donald Trump, who said he is "bringing out the military" to address what he called a national emergency.

The additional troops are to provide what one official described as logistical support to the Border Patrol. This would include a variety of things such as vehicles, tents and equipment.

There are already about 2,000 National Guard troops assisting at the border under a previous Pentagon arrangement.