Trump's wall directive largely symbolic

It is not known whether Donald Trump has ever listened to British rock band Pink Floyd's seminal album "The Wall."

What is known, however, is that his promise to build what he repeatedly described as "a big, beautiful wall" along the US-Mexican border became the early rallying cry for Trump's supporters, helped catapult him to the top of the field of Republican presidential contenders, and ultimately win the White House.

So it doesn't come as much of a surprise that Trump on Wednesday signed an executive order focusing on one of his key, and most contentious, campaign vows: to build a wall along the US' southern border with Mexico.

In brief remarks reminiscent of his campaign speeches on the issue of border security and illegal immigration at the Department of Homeland Security (DHS), President Trump vowed to make good on his election promise and said the Department would immediately start with the construction of a border wall.

Limited power

"As president, I have no higher duty to protect the lives of the American people," Trump said in front of an audience that noticeably featured several rows of uniformed officers vowing to end what he called a "crisis on our southern border."

But despite the presidential directive signed by Trump Wednesday towards building a wall, it is unlikely that a physical, continuous wall will be erected alongside the Mexican border any time soon - or ever.

"The executive order today is largely symbolic," said Steve Yale-Loehr, a professor of immigration law at Cornell University, who co-wrote the leading 21-volume legal treatise on the issue.

"Experts have estimated that if he truly wanted to build a wall along the entire 2000-mile (3,200-kilometer) border it would cost between 15 and 25 billion dollars," he added. "That's a lot of money and there is so only so much he can do by himself without asking Congress for that money."

It's a symbolic move, concurred Jennifer Gordon, who specializes in immigration law at Fordham University: "He doesn't have the power of appropriation to give money to that, he needs Congress for that."

Trump can direct the DHS to allocate existing funds towards the purpose of building a wall, but such funds, noted the scholars, will nowhere be near what is required to complete such a large project.   

'Layered approach'

That means that the Republican-controlled Congress would have to appropriate the billions necessary to fund Donald Trump's border wall plan. And this is where the president's project is likely to run into problems, noted Yale-Loehr, because while Republicans generally support increased border security measures, they will be reluctant to back a continuous border wall with such a steep price tag and questionable security benefits. Mexico has already said it won't pay for the project.   

"I think Congress will fund some more money toward continued construction of fencing, but I doubt that they will be able to fund the entire wall or do it the way that Trump had proposed on the campaign trail," said Yale-Loehr, pointing out that even Trump's new DHS chief John Kelly in his confirmation hearing had spoken of a "layered approach."

That means a whole range of measures, including drones, more border officers, negotiations with other countries as well as increased fencing, but not necessarily a wall. "So I think we will see more of that approach than actually funding to build a physical structure," said Yale-Loehr.

What's more, said Fordham University's Gordon, the new DHS chief Kelly's position of a layered approach is shared by many security experts "who are sophisticated and believe in more border security."

'Caveman solution'

"A wall is sort of the caveman solution," she added. "It's a big symbolic project, but it's a lot of money to spend on a symbol."

A more effective move, would be to better detect people who overstay their visas, a group that makes up half of all people residing illegally in the US, said Yale-Loehr.

Asked whether she believes a continuous, physical wall along US-Mexican border will become reality under the Trump administration, Fordham University's Gordon said: "No, I do not.”

"I do not think I will see a great, big, beautiful wall," agreed her colleague Yale-Loehr. "He may have one or two miles of a big, beautiful wall for photo opportunities, but it is not going to encompass the entire 2000 miles."