Donald Trump has issued an executive order for an "impassable physical barrier" which has to be built along the US border with Mexico. He also signed an action to strip funds from US cities that are sanctuaries for undocumented immigrants.

Trump declared in a TV interview with ABC News that Mexico would absolutely, 100% reimburse the US for his wall along the border.

But Congress would have to approve funding for the structure, which is going to to cost billions of dollars.

A nation without borders is not a nation

He spoke of a crisis on the southern border as he signed the directives at the Department of Homeland Security on Wednesday. The orders also called for hiring 10,000 immigration officials to increase border security.

"A nation without borders is not a nation," Trump declared. "Beginning today the United States gets back control of its borders."

He is also expected to announce immigration restrictions from seven African and Middle Eastern countries, including Yemen, Syria, and Iraq.

Sanctuary cities

The term applies to cities in United States that have policies in place to limit the assistance given to federal immigration authorities.

It became popular in the 1980s after Los Angeles told its police to stop questioning people solely to determine their immigration status in 1979. And in 1989, San Francisco passed an order that banned the use of city funds to enforce federal immigration laws.

Officials in cities such as Los Angeles, Chicago, New York, Philadelphia, Boston, Washington, Denver, San Francisco and Seattle give some type of protection to illegal immigrants. 

Mexico will pay for the wall

"There will be a payment. It will be in a form, perhaps a complicated form," Trump said. The Mexico has refused to pay for that wall and many mexicans see that measure as racism.

Trump estimated the wall would cost $8bn, but critics believe that it could cost almost twice that amount of money.

This week Trump claimed that between three and five million illegals had voted for Hillary Clinton, but offered no evidence.