WASHINGTON — President Trump’s executive order on immigration quickly reverberated through the United States and across the globe on Saturday, slamming the border shut for an Iranian scientist headed to a lab in Boston, an Iraqi who had worked for a decade as an interpreter for the United States Army, and a Syrian refugee family headed to a new life in Ohio, among countless others.
Around the nation, security officers at major international gateways had new rules to follow, though the application of the order appeared uneven. Humanitarian organizations scrambled to cancel long-planned programs, delivering the bad news to families who were about to travel. Refugees who were on flights when the order was signed were detained at airports.
“We’ve gotten reports of people being detained all over the country,” said Becca Heller, the director of the International Refugee Assistance Project. “They’re literally pouring in by the minute.”
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 student at Stanford University was blocked for hours from returning to California.
The Department of Homeland Security said that the executive order also barred green card holders from those countries from re-entering the United States. In a briefing for reporters on Saturday, White House officials said that green card holders from the seven affected countries who are outside the United States would need a case-by-case waiver to return to the United States.
Legal residents who have a green card and are currently in the United States should meet with a consular officer before leaving the country, a White House official, who spoke on the condition of anonymity, told reporters. Officials did not clarify the criteria that would qualify someone for a waiver from the president’s executive order, which says only that one can be granted when it is “in the national interest.”
But the week-old administration appeared to be implementing the order chaotically, with agencies and officials around the globe interpreting it in different ways.
The Stanford student, a legal permanent resident of the United States with a green card, was held at Kennedy International Airport in New York for about eight hours but was eventually allowed to fly to California, said Lisa Lapin, a Stanford spokeswoman. Others who were detained appeared to be still in custody or sent back to their home countries.
White House aides claimed on Saturday that there had been talks with officials at the State Department and the Department of Homeland Security over the past several weeks 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. Two of the officials said leaders of Customs and Border Protection and Citizenship and Immigration Services — the two agencies most directly affected by the order — and other agencies were on a telephone briefing on the new policy even as Mr. Trump signed it on Friday.
At least one case prompted a legal challenge as lawyers representing two Iraqi refugees held at Kennedy Airport filed a motion early Saturday seeking to have their clients released. They also filed a motion for class certification, in an effort to represent all refugees and other immigrants who they said were being unlawfully detained at ports of entry.
“What I do for this country? They put the cuffs on,” Mr. Darweesh said. “You know how many soldiers I touch by this hand?”
The other man the lawyers are representing, Haider Sameer Abdulkhaleq Alshawi, remained in custody as his legal advocates sought his release.
Inside the airport, one of the lawyers, Mark Doss, a supervising attorney at the International Refugee Assistance Project, asked a border agent, “Who is the person we need to talk to?”
“Call Mr. Trump,” said the agent, who declined to identify himself.
The White House said the restrictions would protect “the United States from foreign nationals entering from countries compromised by terrorism” and ensure “a more rigorous vetting process.” But critics condemned Mr. Trump over the immediate collateral damage imposed on people who, by all accounts, had no sinister intentions in trying to come to the United States.
Peaceful protests began forming Saturday afternoon at Kennedy Airport, where nine travelers had been detained upon arrival at Terminal 7 and two others at Terminal 4, an airport official said.
The official said they were being held in a federal area of the airport, adding that such situations were playing out around the nation.
An official message to all American diplomatic posts around the world provided instructions about how to treat people from the countries affected: “Effective immediately, halt interviewing and cease issuance and printing” of visas to the United States.
Internationally, confusion turned to panic as travelers found themselves unable to board flights bound for the United States. In Dubai and Istanbul, airport and immigration officials turned passengers away at boarding gates and, in at least one case, ejected a family from a flight they had boarded.
But Professor Michel said the visas for the student and his wife had been indefinitely suspended.
“This outstanding young scientist has enormous potential to make contributions that will improve our understanding of heart disease, and he has already been thoroughly vetted,” Professor Michel wrote to The New York Times.
Peter McPherson, the president of the Association of Public and Land-grant Universities, which represents many of the biggest public colleges in the country, said he was “deeply concerned” about the new policy. He said it was “causing significant disruption and hardship” for students, researchers, faculty and staff members.
A Syrian family of six who have been living in a Turkish refugee camp since fleeing their home in 2014 had been scheduled to arrive in Cleveland on Tuesday, according to a report in The Cleveland Plain Dealer. Instead, the family’s trip has been called off.
Danielle Drake, a community relations manager at US Together, a refugee resettlement agency, told the newspaper that Mr. Trump’s ban reminded her of when the United States turned away Jewish refugees during World War II. “All those times that people said, ‘Never again,’ well, we’re doing it again,” she said.
On Twitter, Daniel W. Drezner, a professor at the Fletcher School of Law and Diplomacy at Tufts University in Medford, Mass., posted an angry message for Mr. Trump after the executive order stopped the arrival of a Syrian family his synagogue had sponsored.
In an interview on Friday night on “The Rachel Maddow Show” on MSNBC, he expressed sorrow for the fate of the family and apologized for cursing in his Twitter message.
“I can’t quite describe the degree of anger that I felt as a reaction to this, which then caused me to curse at the president on social media,” he said, adding, “which is probably something I should not do as a general rule.”
A Christian family of six from Syria said in an email to Representative Charlie Dent, Republican of Pennsylvania, that they were being detained at Philadelphia International Airport on Saturday morning despite having legal paperwork, green cards and visas that had been approved.
In the case of the two Iraqis held at Kennedy Airport, the legal filings by his lawyers say that Mr. Darweesh was granted a special immigrant visa on Jan. 20, the same day Mr. Trump was sworn in as president. Mr. Darweesh worked with the Americans in Iraq in a variety of jobs — as an engineer, a contractor and an interpreter for the Army’s 101st Airborne Division in Baghdad and Mosul starting shortly after the invasion of Iraq on April 1, 2003.
A husband and father of three, he arrived at Kennedy Airport with his family. Mr. Darweesh’s wife and children made it through passport control and customs, but agents of Customs and Border Protection detained him.
In Istanbul, during a stopover on Saturday, passengers reported that security officers had entered a plane after everyone had boarded and ordered a young Iranian woman and her family to leave the aircraft.
Iranian green card holders who live in the United States were blindsided by the decree while on vacation in Iran, finding themselves in a legal limbo and unsure whether they would be able to return to America.
“How do I get back home now?” said Daria Zeynalia, a green card holder who was visiting family in Iran. He had rented a house and leased a car, and would be eligible for citizenship in November. “What about my job? If I can’t go back soon, I’ll lose everything.”