The administration issued a new policy Thursday that would give President Trump power to block asylum claims from the migrant caravan and other illegal immigrants who jump the U.S. -Mexico border.
"Those who enter the country between ports are knowingly and voluntarily breaking the law", said one official.
The regulations released, in conjunction with an order expected to be signed by President Donald Trump, would effectively ban migrants who cross the USA border with Mexico illegally from qualifying for asylum.
The American Civil Liberties Union (ACLU) branded the presidential decree "illegal".
The issue of the country's loose asylum laws - where foreign nationals can claim that they fear for their lives in their native country and be released into the US until their day in court - has sparked debate as a caravan of 7,000 to 10,000 Central Americans heads to the U.S.
People have to come into the United States at points of entry, Mr Trump said, before leaving for Paris.
Asylum seekers turn themselves in to a US Border Patrol agent after crossing from Mexico into the United States.
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The appointment generated immediate controversy given Mr Whitaker's previous public comments criticising the probe. The special counsel has also been investigating whether Mr Comey's firing amounted to obstruction of justice.
United States law gave migrants seeking asylum a legal obligation to have their claims heard if they feared violence.
The proclamation put into effect a new rule the Trump administration entered into the federal registry on Friday that would ban migrants from applying for asylum outside of official ports of entry. A USA asylum officer then conducts an interview to determine if the person has a "credible fear" of persecution, in which case the applicant is typically assigned a court date and released from custody.
POTUS initially revealed his administration's intentions last week during a speech at the White House in which he indicated that he was "finalizing a plan" to deny asylum claims from those who illegally enter the US.
In 2017, the USA fielded more than 330,000 asylum claims, almost double the number two years earlier and surpassing Germany as highest in the world.
Senior US administration officials said during a conference call on Thursday that they were working to ensure they had the resources and manpower at the ports of entry to prepare for any large number of asylum seekers arriving at the border.
With so many asylum seekers arriving at border crossings, USA customs officers have been limiting the number of people allowed to approach the pedestrian entry lanes, a tactic known as "metering" that has triggered challenges in federal court.
"Ports of entry. are overcrowded", said Jonathan Ryan, executive director of RAICES, a Texas-based immigrant defense group. But many migrants are unaware of that guidance, and official border crossings have grown clogged. The caravan is now around 600 miles from the United States.