Trump is sending thousands of troops to the border with Mexico - here's where they're going and what they're doing

• The number of active-duty military personnel to be deployed to the US-Mexico border in support of Operation Faithful Patriot has surged to more than 7,000 according to the latest Department of Defense estimates.
• Last week, the number was said to be in the hundreds.
• "This is a response to the caravan directed by the president," Secretary of Defense Jim Mattis told reporters Sunday, referring to the migrant caravans approaching America's southern border.
• While critics have accused the Trump administration of engaging in a political stunt ahead of midterm elections, Mattis argued Wednesday that "we don't do stunts in this department."

The US military is sending thousands of troops to the US-Mexico border in preparation for the arrival of migrant caravans determined to enter the US.

The operation, known as Faithful Patriot, is expected to involve more than 7,000 active-duty troops, the Department of Defense estimated in a press statement released late Wednesday. This is in addition to the over 2,000 National Guard personnel deployed to the border for Operation Guardian Support, US Northern Command explained to Business Insider.

The troops deployed as part of Operation Faithful Patriot are advancing the Customs and Border Protection mission by providing planning, engineering, transportation, logistics, and medical support. These military units will serve in a limited, Title 10 capacity, engaging in activities such as barrier construction, airlift, and medical treatment.

Active-duty US military personnel are being deployed to the following locations:

Arizona:Davis-Monthan Air Force Base and Fort Huachuca

Texas: Fort Bliss, Joint Base San Antonio, Naval Air Station Corpus Christi, Naval Operations Support Center Harlingen, and Naval Air Station Kingsville

California: Marine Corps Air Station Miramar, Marine Corps Base Camp Pendleton, Naval Air Facility El Centro, Naval Base Coronado, Naval Base San Diego, and Naval Base Point Loma

The US military is sending military police, engineers, helicopter teams, command and military planning units, medical teams, transportation and logistics teams to the border. The units heading south are coming from bases across ten different states.

The planning teams will coordinate operations and support missions, medical personnel will triage, treat, and prepare patients for transport, the engineers will construct erect light towers and build barriers, and the helicopter teams will facilitate the movement of CBP tactical teams.

The Department of Defense says the number of troops deployed could change at any time, potentially on a daily basis. Changes will be made in accordance with operational demands, the press release explained.

"We'll do up to anywhere between 10 [sic] and 15,000 military personnel, on top of border patrol, ICE and everybody else at the border," Trump said Wednesday afternoon, adding, "Nobody's coming in."

The president previously characterized the approaching caravans as an "invasion," warning the migrants that the military will be waiting for them when they arrive.