As dawn breaks on a new era in American immigration policy, a young boy peels and eats a clementine in the gap between the border fence that separates the United States and Mexico.

A teenage girl wraps herself in a silver thermal blanket and a man passes his mobile phone through the metal slats in the fence for someone on the other side to charge.

They are the lucky ones, in a way, because they are among the final group of migrants to enter the United States before the introduction of a new border policy.

The executive order, issued by President Biden, will temporarily seal the border along the southern states if illegal crossings exceed 2,500 people a day, which they do on a regular basis at the moment.

The order had been a closely guarded secret, until it wasn’t. President Biden used the announcement to criticize Republicans in Congress for failing to pass a bipartisan bill on the border and defend his own immigration policy.

“This action will help us gain control of our border, restore order into the process,” he said. “If the United States doesn’t secure our border, there’s no limit to the number of people who may try to come here. Doing nothing is not an option, we have to act.”

It represented a sharp about-turn for a man who came to power criticizing Donald Trump’s draconian action to curb immigration but is now making moves reminiscent of his predecessor.