(CNN) The Pentagon has approved additional military support for the Department of Homeland Security on the southern border, making it less likely that US troops, whose deployment to the border began in the fall, will return home at the end of this month as originally scheduled.

"In response to the December 27, 2018 request from the Department of Homeland Security , Acting Secretary of Defense Pat Shanahan approved Department of Defense assistance to DHS through Sept. 30, 2019," the Pentagon's statement read.

The statement added that the US military "is transitioning its support at the southwestern border from hardening ports of entry to mobile surveillance and detection, as well as concertina wire emplacement between ports of entry."

By the end of November, the military had already placed over 10 miles of wire obstacles in Texas, Arizona and California.

Read More