WASHINGTON — President Donald Trump has invoked a centuries-old immigration law to ramp up deportations of undocumented migrants amid signs of frustration within the administration over the pace of efforts to deliver on one of his top priorities.

Trump invoked powers under the Alien Enemies Act of 1798 — a law once used to justify the internment of Japanese Americans during World War II — in a proclamation Saturday targeting Tren de Aragua, a Venezuelan gang also designated a foreign terrorist organization.

Many of Tren de Aragua’s members “have unlawfully infiltrated the United States and are conducting irregular warfare and undertaking hostile actions” against the country, Trump said in the proclamation. The president also argued the operation is engaging in “mass illegal migration to the United States” in a bid to harm the country’s citizens, undermine public safety and support efforts by Venezuela President Nicolas Maduro to destabilize democratic nations.

The law allows the government to detain and remove noncitizens of hostile nations in wartime, powers which have been tapped rarely in U.S. history.

Even before Trump’s proclamation was made public, opponents had gone to court to challenge its use. James E. Boasberg, chief judge of the U.S. District Court for the District of Columbia, on Saturday issued a temporary restraining order blocking the deportation of five Venezuelans under the wartime statute. Boasberg’s order bars the deportation of the Venezuelan citizens for 14 days, unless the court takes further action.

Trump’s declaration is likely to draw even more legal challenges and demonstrates how Trump — just as he did in his first term — is testing the boundaries of his presidential powers over immigration. Many of Trump’s immigration actions are already being weighed by the courts, including an order seeking to end automatic birthright citizenship and his bid to deport a Palestinian activist Mahmoud Khalil, who helped lead anti-Israel protests at Columbia University.

Trump in his second term has moved to ramp up deportations of undocumented migrants and secure U.S. borders in the wakes of a 2024 presidential election in which he rode to office in part on voter anxiety over illegal immigration and crime.

The crackdown has seen high-profile raids across the U.S. and the use of deportations flights — including some on military planes — but that pace has slowed and there have been indications of angst within the administration over its ability to quickly carry out the president’s directives, including changes to senior personnel at U.S. Immigration and Customs Enforcement. Trump has urged Congress to provide additional funding to speed up deportations and complete the construction of a wall along the U.S.-Mexico border started in his first term.

Trump’s decision to seize wartime powers is likely to feed criticism of his moves on immigration. Under the law, the president has the authority to invoke the act in times of “declared war” or when a foreign nation or government has invaded the U.S.

Upon taking office, Trump declared a national emergency at the southern border and directed the Pentagon to deploy additional resources to address the situation. He also signed an executive order that designated cartels and other organizations as Foreign Terrorist Organizations and Specially Designated Global Terrorists and directed the U.S. attorney general and Homeland Security secretary to work with the Secretary of State on potentially implementing the Alien Enemies Act.

Trump on the campaign trail had vowed to use the act — and regularly cited cases of crime where migrants who crossed the border illegally were suspects or convicted. In October, Trump visited the town of Aurora, Colorado, seizing on surveillance video which showed heavily armed men in the town forcing their way into an apartment. Trump used the incident to make unsubstantiated claims — disputed by local officials — that the town was overrun by Venezuelan gang members.

The administration has seen a decline in unauthorized crossings at the southern border. In February, Border Patrol agents recorded 8,300 illegal crossings, the lowest monthly total in decades.

The president has also used tariffs to pressure Mexico and Canada to do more to secure the border and directed agencies to identify federally funded programs providing benefits to migrants in the country illegally.

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(With assistance from Jennifer A. Dlouhy.)

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