WASHINGTON — The Pentagon says it will send 3,750 more troops to the U.S.-Mexico border to put up another 150 miles of concertina wire and provide other support for Customs and Border Protection.

The additions announced Sunday will bring the total number of active-duty troops on the border to 4,350.

The announcement is in line with what Acting Defense Secretary Pat Shanahan had said on Tuesday when he provided estimates for the next phase of a military mission that critics have derided as a political ploy by the White House.

Shanahan said several thousand more troops would be sent mainly to install additional wire barriers and provide a large new system of mobile surveillance and monitoring of the border area. Sunday’s announcement said the mobile surveillance mission would last through Sept. 30.