U.S. President Donald Trump declared a national emergency at the U.S.-Mexico border during remarks about border security and announced that he will indeed build his border wall by Executive Order. Senior administration officials explained that the money (which adds up to more than $8 billion – much more than the $5.7 billion the President had been requesting) will come from the following areas:
$1.375 billion from the Homeland Security appropriations bill
$600 million from the Treasury Department’s drug forfeiture fund
$2.5 billion from the Department of Defense’s drug interdiction program
$3.6 billion from the Department of Defense’s military construction account.
A congressional aide, who spoke on condition of anonymity, said Trump could theoretically divert up to $21 billion in military construction funds that aren't already obligated for use on border projects. Much of the $21 billion could be taken from the "wartime funds" account, which is known as the overseas contingency operations, or OCO. "[The president] is free to spend without a vote from Congress," the aide said of the immediately available $21 billion. "He has to notify Congress of what he's done but he doesn't have to come to Congress to do it."