By Michael D. Shear

New York Times News Service

WASHINGTON — The Trump administration, invoking national security powers meant to protect the United States against threats from abroad, announced rules Thursday that give President Donald Trump vast authority to deny asylum to virtually any migrant who crosses the border illegally.

Administration officials declined to say who will be affected, but it is widely expected inside the government and by advocate groups that Trump intends to deny asylum to migrants from Central American nations, some of whom are marching toward the United States in a caravan.

The president is expected to announce Friday which countries the rules will apply to. They will go into effect on an emergency basis as soon as they are published in the Federal Register.

The regulations will overhaul long-standing asylum laws that provide the opportunity for people fleeing persecution and violence in their home countries to seek sanctuary in the United States.

“The law is clear: People can apply for asylum whether or not they’re at a port of entry, and regardless of their immigration status,” said Omar Jadwat, director of the American Civil Liberties Union’s Immigrants’ Rights Project. “The president doesn’t get to ignore that law, even if he dislikes it.”

The new regulations draw upon the same authority Trump used to ban travel from several predominantly Muslim countries and are certain to be challenged in court.