In a second Twitter message on Sunday, the president said that the United States needed strong borders and “extreme vetting” to protect itself from terrorists. He cited Europe and “indeed, the world” as evidence that the United States must shut its borders to potential threats.
The president’s order, enacted with the stroke of a pen at 4:42 p.m. Eastern on Friday, suspended entry of all refugees to the United States for 120 days, barred Syrian refugees indefinitely and blocked entry into the United States for 90 days for citizens of seven predominantly Muslim countries: Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen.
A series of rulings by federal judges across the country blocked part of the president’s actions, preventing the government from deporting some travelers who found themselves ensnared by the presidential order. But the court decisions largely stopped short of letting them into the country or issuing a broader ruling on the constitutionality of Mr. Trump’s actions.
Lawyers for those denied entry said on Sunday that there was significant confusion and disagreement among border agents about who was affected by Mr. Trump’s order.
In a statement Sunday morning, the Department of Homeland Security said that agents would “continue to enforce all of President Trump’s executive orders,” and that “prohibited travel will remain prohibited.” But it also said that the department “will comply with judicial orders.”
The confusion was evident in the handling of those who have valid green cards, making them legal permanent residents of the United States.
On Saturday night, the Department of Homeland Security said that Mr. Trump’s order did apply to green card holders who were traveling to the United States from the seven countries affected.
White House officials reiterated that position in a briefing for reporters on Saturday afternoon, saying that green card holders from the seven countries would need a case-by-case waiver to return.
Mr. Priebus appeared to change that position Sunday morning. “As far as green card holders, moving forward, it doesn’t affect them,” he said on NBC’s “Meet the Press” program.
He defended Mr. Trump’s order, saying it had been carried out smoothly and was protecting Americans from terrorist threats. On Saturday, a day after the order was issued, airports were marked by scenes of confusion and protest as officials tried to interpret the order, including how to handle green card holders.
Around the globe on Saturday, legal residents of the United States who hold valid green cards and approved visas were blocked from boarding planes overseas or detained for hours in American airports.
Mr. Priebus said several times during the NBC interview that green card holders would not be subject to the order “going forward.” But he repeatedly suggested that anyone, including American citizens, who traveled from any of the seven predominantly Muslim countries identified in the order would be subjected to additional scrutiny.
“If you’re an American citizen traveling back and forth to Libya, you are likely to be subjected to further questioning when you come into an airport,” Mr. Priebus said. He added later, “There is discretionary authority that a customs and border patrol agent has when they suspect that someone is up to no good when they travel back and forth to Libya or Yemen.”
Mr. Priebus said that travelers from the seven countries would be “subjected, temporarily, with more questioning, until a better system is put in place.”
Mr. Trump — in office just a week — has found himself accused of constitutional and legal overreach with his executive order. Large crowds of protesters turned out at airports around the country to denounce Mr. Trump’s ban.
Lawyers who sued the government to block the White House order said the judge’s decision could affect an estimated 100 to 200 people who were detained upon arrival at American airports.
Judge Ann M. Donnelly of Federal District Court in Brooklyn, who was nominated by former President Barack Obama, ruled just before 9 p.m. Saturday that carrying out Mr. Trump’s order by sending the travelers home could cause them “irreparable harm.” She said the government was “enjoined and restrained from, in any manner and by any means, removing individuals” who had arrived in the United States with valid visas or refugee status.
The ruling does not appear to force the administration to let in people otherwise blocked by Mr. Trump’s order who have not yet traveled to the United States.
The judge’s one-page ruling came swiftly after lawyers for the American Civil Liberties Union testified in her courtroom that one of the people detained at an airport was being put on a plane to be deported back to Syria at that very moment.
Hundreds of people waited outside the courthouse chanting “Set them free!” as lawyers made their case. When the crowd learned that Judge Donnelly had ruled in favor of the plaintiffs, a rousing cheer went up in the crowd.
Minutes after the judge’s ruling in New York, another judge, Leonie M. Brinkema of Federal District Court in Virginia, issued a temporary restraining order for a week to block the removal of any green card holders being detained at Dulles International Airport.
Throughout the day on Saturday, there were numerous reports of students attending American universities who were blocked from returning to the United States from visits abroad. One student said in a Twitter post that he would be unable to study at Yale. Another who attends the Massachusetts Institute of Technology was refused permission to board a plane. A Sudanese graduate student at Stanford University was blocked for hours from entering the country.
Human rights groups reported that legal permanent residents of the United States who hold green cards were being stopped in foreign airports as they sought to return from funerals, vacations or study abroad.
The White House said the restrictions would protect “the United States from foreign nationals entering from countries compromised by terrorism” and allow the administration time to put in place “a more rigorous vetting process.” But critics condemned Mr. Trump over the collateral damage on people who had no sinister intentions in trying to come to the United States.
White House aides said on Saturday that there had been consultations with State Department and homeland security officials about carrying out the order. “Everyone who needed to know was informed,” one aide said.
But that assertion was denied by multiple officials with knowledge of the interactions, including two officials at the State Department. Leaders of Customs and Border Protection and of Citizenship and Immigration Services — the two agencies most directly affected by the order — were on a telephone briefing on the new policy even as Mr. Trump signed it on Friday, two officials said.