(CNN) The Pentagon received a Department of Homeland Security request Wednesday to build and pay for hundreds of additional miles of border wall on the southwest border, according to the Department of Defense.

The request is for roughly 270 miles of border barrier and other infrastructure to be built in areas that are considered drug corridors, a mix of rural and urban areas, a senior Department of Defense official told CNN.

Because the request is to ostensibly help combat drug smuggling, the Pentagon will be allowed to construct these barriers under its pre-existing "284" counter drug authority, which allows the Defense Department to build barriers, lighting and roads for the purpose of countering drug trafficking, according to the official.

The Pentagon will take about two weeks to put the request through an assessment involving the US Army Corps of Engineers, the Army Secretary, Defense Department lawyers and the Joint Staff and the Comptroller, the latter of which will assess where funds can be found to support additional construction, added the official.

Once the assessment is completed, Secretary of Defense Mark Esper will make a determination to approve all, some or none of the request.

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