Officials at the Department of Homeland Security and Pentagon said they are cutting the number of troops and changing their mission on the Southwest border of the US.

The drawdown will begin in January and should be completed by March, said a CNN report, and will reduce the number of National Guard troops on the border from 1,200 with responsibilities mainly on the ground to 300 who will support the border mission in the air.

DHS said the change is possible because of a jump in the number of Border Patrol officers in the region, an increase in technology and a drop in apprehensions at the border.

In a news release, DHS and the Pentagon did not cite exactly how many troops would be pulled from the border, but said the "new strategic approach" will increase border security. That approach includes "adding a number of new multi-purpose aerial assets" equipped with the "latest surveillance and reconnaissance capabilities."

In addition, the National Guard will provide helicopters and planes to the Border Patrol, "allowing for faster response capabilities," the news release said.