Citing President Trump's extraordinary move to close the American asylum system, U.S. border agents have been instructed to summarily deport migrants crossing into the country illegally without allowing them to request legal protection, according to internal government documents and agency officials.

Just hours after being sworn in, Mr. Trump invoked sweeping presidential authorities to bar the entry of migrants deemed to be participating in an "invasion" of the U.S., as well as those who may pose a public health or national security risk. He cited a provision of immigration law known as 212(f) that allows presidents to suspend the entry of foreigners whose entry is deemed to be "detrimental" to the U.S.

In that same proclamation, Mr. Trump cited his constitutional powers over foreign affairs to empower U.S. immigration officials to "repel, repatriate, or remove any alien engaged in the invasion across the southern border of the United States."