US President Donald Trump on Monday initiated a sweeping immigration crackdown, deploying the military to aid border security, imposing a broad asylum ban, and moving to restrict citizenship for children born on US soil.

Declaring illegal immigration a national emergency, Trump directed the Pentagon to support border wall construction, expand detention space, and assist in migrant transportation. The secretary of defence was empowered to deploy troops to the border as necessary.

Trump reinstated his "remain in Mexico" programme, requiring non-Mexican migrants to await the resolution of their US cases in Mexico. Shortly after his inauguration, US border authorities terminated outgoing President Joe Biden’s CBP One entry programme, which had allowed legal migrant entry via app-based appointments. Existing appointments were cancelled, leaving migrants in disarray.

Trump, who regained the presidency on promises to bolster border security and escalate deportations, criticised Biden for high levels of illegal immigration. While Biden tightened policies last year, leading to reduced illegal crossings, Republicans argue that large-scale deportations are necessary following millions of illegal entries during Biden’s presidency.

Estimates suggest there were 11 million immigrants without legal status or with temporary status in early 2022, a figure some analysts now place between 13 and 14 million.

“As commander-in-chief, I have no higher responsibility than to defend our country from threats and invasions, and that is exactly what I am going to do,” Trump said in his inaugural address.

Critics, including immigrant advocates, argue that mass deportations could harm businesses, separate families, and cost taxpayers billions. The American Civil Liberties Union (ACLU) filed a federal court challenge against the termination of CBP One, describing it as the sole avenue for asylum seekers at the border.

Biden entry programme shut down

In Mexican border cities, migrants faced cancelled CBP One appointments shortly after Trump’s inauguration. By early January, 280,000 people were logging into the app daily to secure appointments.

Migrants in Ciudad Juárez scrambled for short-term housing and transport, uncertain about their next steps.

Daynna del Valle, a 40-year-old Venezuelan, had waited eight months in Mexico for an appointment due on Tuesday. Her nail salon earnings barely sufficed to support her mother in Colombia, a cancer survivor needing treatment.

“I’m lost,” she said. “I don’t know what to do, where to go.”

In Piedras Negras, Denia Méndez, a Honduran migrant, discovered her appointment had been cancelled. Her 15-year-old daughter Sofia tried unsuccessfully to access the app. “They’re not going to let you into the app, baby,” Méndez told her.

Birthright citizenship targeted

Trump ordered agencies to deny citizenship to children born in the US without at least one citizen or permanent resident parent, effective in 30 days. The ACLU filed a lawsuit, arguing that the order violated the 14th Amendment’s Citizenship Clause.

“Denying citizenship to US-born children is not only unconstitutional – it’s also a reckless and ruthless repudiation of American values,” said ACLU Executive Director Anthony Romero.

Trump also suspended US refugee resettlement for three months and initiated a review of security protocols for travellers from certain countries, potentially reinstating travel bans.

The administration broadened US Immigration and Customs Enforcement (ICE) enforcement to target migrants with final deportation orders and began moves to designate criminal cartels as terrorist organisations.

Three senior immigration court officials were fired as part of efforts to bring immigration courts under Justice Department control, sources said. The administration also explored invoking the 1798 Alien Enemies Act to address foreign gang members.