WASHINGTON — President Trump proclaimed on Friday that the illegal entry of immigrants across the southern border of the United States is detrimental to the national interest, triggering tough changes that will deny asylum to all migrants who do not enter through official border crossings.
The proclamation, issued just moments before Mr. Trump left the White House for a weekend trip to Paris, suspends asylum rights for all immigrants who attempt to cross into the United States illegally, though officials said it was aimed primarily at several thousand migrants traveling north through Mexico in caravans.
“The continuing and threatened mass migration of aliens with no basis for admission into the United States through our southern border has precipitated a crisis and undermines the integrity of our borders,” Mr. Trump wrote in the proclamation.
[Read Mr. Trump’s proclamation targeting the caravan and asylum seekers.]
As he left the White House for the overseas trip, Mr. Trump said, “We want people to come into our country, but they have to come into the country legally.”
Administration officials said the suspension of asylum rights would be in effect for at least 90 days, but could end sooner if Mexico’s government would sign an agreement allowing the United States to return those who illegally cross the border from Mexico, regardless of their home country — a proposal that Mexico has long rejected.
For decades, immigration law in the United States has required that officials allow migrants who fear persecution in their home countries to seek asylum regardless of whether they entered the United States legally or crossed illegally.
Mr. Trump’s proclamation is a radical departure from that tradition. With the exception of children arriving without parents, officials said that all migrants who cross illegally would automatically be denied asylum.
Officials said migrants would be allowed to seek other protections if they could prove a risk of being tortured in their home countries. Those claims are purposely much harder to prove. The only way to seek asylum will be to arrive at an official border crossing.
But officials conceded that many of the crossings from Mexico into the United States — known as ports of entry — are over capacity and already have trouble processing the number of asylum claims being made by migrants there. Under the new policy, many more are expected to arrive at the crossings.
In the proclamation, Mr. Trump acknowledged the problem and directed his administration “to commit additional resources to support our ports of entry at the southern border to assist in processing those aliens.”
Mr. Trump’s proclamation drew on the same powers to control the nation’s borders that he cited when he banned travel from several predominantly Muslim nations shortly after becoming president. The Supreme Court upheld a later version of that ban after a nearly year-and-a-half legal fight.
The new proclamation is certain to spark a similar legal battle.
For months before the midterm elections, Mr. Trump cast the group of migrants as a threat to national security, claiming — without evidence — that among them are criminals and “unknown Middle Easterners.”
Mr. Trump’s proclamation puts into effect regulatory changes announced Thursday afternoon that effectively overhaul deep-rooted asylum laws that sought to provide a safer life in America for people fleeing violence and persecution in their home countries. Officials said the changes will take effect early Saturday morning.
Most of the migrants in the caravan come from Honduras and other Central American nations, where they say they fear for their lives because of continuing violence.
Mr. Trump has been seething for months about the increase of immigrants crossing into the United States from Mexico and the caravan of several thousand migrants whose travels have drawn media attention. The president ordered more than 5,000 active-duty troops to the border to prevent the migrants from crossing.
By early this week, that caravan still had about 4,000 or 5,000 people and had made it to Mexico City.