The Defense Department is expanding its border role with a new military zone near Yuma, aiming to boost surveillance as crossings continue to fall.

The US Navy and Air Force are expected to announce the establishment of two additional military zones along the US southern border this week, three US officials told CNN.

The Pentagon will create two new military zones along the border with Mexico, U.S. officials said on Wednesday, a move that allows troops to temporarily detain migrants or trespassers. President Donald Trump's administration has hailed its actions along the border,