Donald Trump has signed an executive order calling for a "large physical barrier" between the US and Mexico - the order will jump-start the process of building the wall, which was one of the President's primary campaign promises.

特朗普已经签署一项行政命令，要求在美国和墨西哥之间修建一座“巨型物理屏障”。该命令将启动造墙工程，这是他的主要竞选承诺之一。

"So badly needed. You folks know how badly needed it is as a help... I believe the steps we will take, starting right now, will improve the safety of both of our countries," Mr Trump said at the Department of Homeland Security (DHS). "A nation without borders is not a nation. Beginning today, the United States gets back control of its borders - gets back its borders."

In addition to the wall, Mr Trump signed an action to strip federal funding from "sanctuary cities", that do not prosecute undocumented immigrants. He has mobilised on most of his controversial campaign promises - including directives against the Affordable Care Act, a greenlight to contentious oil pipelines, withdrawal from the Trans-Pacific trade agreement, and the renewal of the "Global Gag Rule", which prevents US funding for global family planning NGOs that are linked to abortion.

He is also expected to take actions this week to limit legal immigration - including more rigorous restrictions to refugee acceptance and blocking the issuance of visas to people from Muslim-majority countries in the Middle East and North Africa.

"Big day planned on national security tomorrow," Mr Trump tweeted on Tuesday night. "Among many other things, we will build the wall."