More troops are expected to be deployed to the Southern border to construct or upgrade 160 miles of fencing and provide medical care to a steady stream of migrant families arriving from Central America, according to military sources.
The deployment and fence construction along the California and Arizona borders would be paid for by the Pentagon, from the Department of Defense's discretionary funding.
The move comes as President Trump continues to demand more than $5 billion from Congress for border security and a wall along the U.S.-Mexico border. Congressional Democrats oppose the move, and parts of the federal government have been shut down because of the impasse.
The Department of Defense has not been affected by the shutdown.
Last month Trump tweeted that "the Military will build the remaining sections of the Wall" after he said that much of it already has been built. The president was referring to several hundred miles of existing fencing along the Southern border.
A few days later, Trump repeated his intention to have the Defense Department do the job, saying in another tweet that because of crime and drugs flowing through the border "the United States Military will build the Wall!"