President Trump defended his controversial immigration order Sunday evening, as lawyers across the country urged immigrants from the seven barred Muslim-majority nations affected to quickly return to the United States — with Boston noted by some as having the best airport to avoid detention.

The White House on Sunday clarified the president’s executive order, saying it did not apply to green card holders unless they are a security threat — easing a key part of Trump’s directive. That announcement followed a day of confusion nationally over how to carry out Trump’s order, and to whom it applies.

On Sunday, lawyers warned that incoming travelers from the seven countries could be subject to long interrogations or be turned away upon arrival at a US airport. The warning was delivered even in Boston, despite a federal judge’s predawn ruling that aimed to keep Trump’s directive from being honored at Logan International Airport.

White House chief of staff Reince Priebus said mid-morning on CBS’s “Face the Nation’’ that 325,000 foreign travelers came into the United States on Saturday, and 109 were detained for further questioning because they came from one of the seven countries.

As of Sunday evening, at least three people arriving at Logan had been identified as being stopped and questioned at length.

“We can’t provide any assurance at this point’’ about how foreign travelers will be treated, said Punam Rogers, an immigration lawyer with the Boston office of Foley Hoag.

The president’s order on Friday halted all refugees from coming to the United States for 120 days, barred Syrian refugees indefinitely, and prevented citizens of seven majority Muslim countries — Iran, Iraq, Libya, Somalia, Sudan, Syria, and Yemen — from entering for 90 days.

Trump late Sunday defended his executive order, saying he was trying to protect America from terrorism, and blasted the news media for its coverage. He said many Muslim-majority nations were not banned and said the seven nations had been identified by the Obama administration as “sources of terror.’’

“To be clear, this is not a Muslim ban, as the media is falsely reporting. This is not about religion — this is about terror and keeping our country safe.’’

Lawyers said Sunday that they hoped immigration officials would obey federal court rulings in New York, Boston, and elsewhere that temporarily halted Trump’s executive order.

Some advocates urged travelers from the affected countries to fly directly to Boston, where two federal judges on Sunday imposed a wide-ranging, albeit temporary, block on Trump’s order that went further than rulings elsewhere.

The judges in Boston barred federal agents from detaining, deporting, or extensively interrogating travelers based on Trump’s order and instructed them to inform airlines overseas of the order.

“Our order is the most expansive order in the country,’’ said Susan Church, one of the lawyers who brought the Boston case. “That seems to be the best protection that somebody could have at this point in time.’’

Others said they would not recommend that all travelers fly through Boston and instead suggested that they avoid airports that aren’t following the court rulings.

“I just think that Boston may not be a panacea,’’ Howard Silverman, a veteran immigration lawyer in Boston, said by phone Sunday from Logan Airport, where he was monitoring arrivals. “Everyone fly into Boston? I don’t think anybody here would want that.’’

The New York ruling, issued Saturday, temporarily barred federal agents from deporting immigrants from those nations because of Trump’s order, though the ruling said officials could still detain them. Lawyers said the New York ruling, and parts of the Boston ruling, applied nationwide.

Confusion abounded on Sunday.

A woman in Watertown wondered what advice to give to a Syrian friend in Lebanon who wanted to book a flight to return to his wife in Massachusetts and his job at CVS.

“We don’t know what to do,’’ said the woman, who is also Syrian but asked not to be identified, for fear of retaliation from the US government. “He said, ‘I need to be back.’ His wife is here. . . . It’s a risk. Either he’s going to be admitted, or not.’’

Adding to the confusion, Trump and the Department of Homeland Security, which oversees customs and immigration agents, issued contradictory statements in response to the court rulings.

Early Sunday, Homeland Security said the government would obey judicial orders, but insisted that Trump’s executive order remained in place.

“No foreign national in a foreign land, without ties to the United States, has any unfettered right to demand entry into the United States or to demand immigration benefits in the United States,’’ the statement said.

Also Sunday, Priebus went on NBC’s “Meet the Press’’ to say the travel ban did not apply to green card holders from the affected nations, contradicting an earlier Homeland Security statement that it did.

The confusion frightened immigrants and infuriated lawyers and lawmakers.

“The statement from the Department of Homeland Security raises more questions than it answers,’’ Senator Edward Markey said in a statement calling on Trump to rescind the order.

Lawyers said travelers from the seven countries should carry copies of the federal court rulings to the airports to show to airport personnel and later to immigration and customs officials, if needed.

And they have been urging travelers to designate someone inside the United States to monitor their arrival.

If immigrants are delayed for questioning at airports — as some were in Boston on Sunday, despite the court ruling — their loved ones should call an attorney who could file a lawsuit on their behalf, lawyers said.

Sunday evening, Homeland Security Secretary John Kelly issued a statement, saying green card holders would be allowed in under Trump’s order, unless they “pose a serious threat to public safety and welfare.’’

“In applying the provisions of the president’s executive order, I hereby deem the entry of lawful permanent residents to be in the national interest,’’ the statement read.

In his late Sunday defense of his executive order, Trump pointed out it was only a temporary halt on travelers from specific nations affected by terrorism so that the United States could ensure that all travelers had been properly vetted.

“America is a proud nation of immigrants, and we will continue to show compassion to those fleeing oppression, but we will do so while protecting our own citizens and border,’’ he said.

But lawyers say customs agents wield broad powers to deport someone — sometimes to dangerous countries — without a hearing before a judge. Some travelers aren’t even allowed to make telephone calls before they are forced back onto an airplane.

“They do have very significant authority,’’ said Boston immigration lawyer Kerry Doyle. “You’re talking about businesses and families and things being disrupted, but you’re also talking about people whose lives are on the line.’’

Milton Valencia and Lisa Wangsness of the Globe staff contributed to this report. Maria Sacchetti can be reached at maria.sacchetti@globe.com.