During the campaign period, President Trump pledged to American citizens that he will build the border wall to protect Americans from illegal immigrants But Democrats have termed the move as ” gross abuse of power.”
He later signed the plan along with a spending bill aimed at preventing a repeat of a recent government shutdown.
He announced the plan after Congress refused to pay for a wall in the bill.
However, senior Democrats immediately said that they would challenge the move in the courts.
If the declaration goes through, Mr Trump will have access to billions of dollars for his project.
The president in his announcement confirmed that the move will allow him to get about $8 billion for the border wall project.
The amount is considerably short of the estimated amount of $23 billion for the completion of the whole project, which should go along 2000 miles (3200km).
“We’re going to confront the national security crisis on our southern border,” Mr Trump said.
“We have an invasion of drugs, invasion of gangs, invasion of people, and it’s unacceptable.
“Everyone knows that walls work.”
However, Mr Trump acknowledged that the move would lead to legal actions that may likely end up to the Supreme Court.
Few hours after the announcement, the first legal challenge against the declaration of national emergency was launched.
A liberal advocacy group, Public Citizen, sued on behalf of a nature preserve and three Texas landowners who have been told the wall may be constructed on their properties.
The matters involving border wall started simply as Trump’s promise during his campaign. The issue became disastrous when Congress failed to accede to the presidents demand of approving funds for the wall project.
Border wall matter has led to a series of government shutdown experienced in the US, a plan which seems to be derailing the economy as no party is willing to go down to the other.