"The Department carefully selected sources for the reprogramming that are excess or early to need and will not adversely affect military preparedness", the document said, as quoted by the newspaper late on Sunday.
According to the document, a part of the funding will be redirected from a programme aimed at modernising the ground infrastructure for the LGM-30G Minuteman III intercontinental ballistic missile.
The Pentagon intends to divert money from a programme related to a system that is used by planes to detect and communicate the position of targets to attack because the programme has been "slightly delayed", the newspaper noted.
The Defence Department will also reallocate money originally given to a "space test experiment" with the participation of the Defence Advanced Projects Research Agency, the newspaper added.
The construction of the wall on the US-Mexican border to prevent the flow of undocumented migrants and drug trafficking to the United States was one of US President Donald Trump's main campaign pledges.
The president, however, has been struggling to find financing for the wall as Congress has refused to allocate billions of dollars from the budget. In order to bypass Congress and secure the necessary funding, Trump declared a state of national emergency on the US southern border.