President Trump continued Monday to adamantly defend his immigration order temporarily banning entry into the United States for migrants from seven Muslim-majority countries and refugees from around the world, despite mounting criticism and questions that stretched from Capitol Hill to the United Nations.
Trump's order has sparked protests from coast to coast, court cases challenging its constitutionality, unease in cities worldwide and a host of questions about the limits of its scope.
The ban's impact continued to reverberate around the world. Refugee groups worried that some 20,000 people could be affected by the 120-day suspension of refugee admission. Lawyers sought to confirm how many people remain detained in the United States, while a lawsuit argued that dozens of people had been forced to give up their green cards by Customs and Border Patrol agents.
Lee Gelernt, deputy director of the ACLU's Immigrants' Rights Project, said the situation at airports remains "chaotic and fluid" and lawyers are "having trouble independently verifying anything because the government will not provide full access to all the detainees."
Gelernt said that by Monday afternoon, no list of detainees had been turned over, adding that the ACLU could be back in court within a day to get the list so it could obtain more definitive information.
On Monday, in what could be the first volley in an intense legal battle, Bob Ferguson, Washington state's attorney general, said he plans to file a federal lawsuit seeking an immediate halt to the order's implementation.
Ferguson is the first state official to declare plans to file such a suit, but he may not be the last. A day earlier, Ferguson joined 15 other state attorneys general in calling the measure unconstitutional. Eric Schneiderman, the New York attorney general who joined in that message, is reviewing possible options "and that could certainly include litigation," Amy Spitalnick, a spokeswoman, said Monday.
White House officials have played down the anger and chaos over the order, holding a briefing with reporters Sunday evening to argue that the rollout was "a massive success story." On Monday, Trump used his now-customary morning tweets to blame others for the disorganized implementation and to minimize its impact on travelers.
Trump's order was followed by two days of intense protests at airport terminals across the country, meaning both weekends of his presidency so far have been marked by heavy public demonstrations against him.
In his tweets Monday morning, Trump had blamed "big problems at airports" on the demonstrators themselves, an airline's technical problems and Senate Minority Leader Charles Schumer, D-N.Y., who teared up while discussing the ban. (Delta suffered technical issues Sunday evening -- 48 hours after Trump signed the immigration order -- that canceled about 150 flights.)
"Only 109 people out of 325,000 were detained and held for questioning," Trump tweeted. "Big problems at airports were caused by Delta computer outage. . ...protesters and the tears of Senator Schumer."
Hours later, former president Barack Obama -- in his first public criticism of Trump since leaving office -- endorsed the protests that have emerged nationwide and rejected his successor's attempt to link the travel ban to the Obama administration.
Obama feels "heartened by the level of engagement taking place in communities around the country," Kevin Lewis, a spokesman for the former president, said in a statement. "Citizens exercising their Constitutional right to assemble, organize and have their voices heard by their elected officials is exactly what we expect to see when American values are at stake."
Alluding to Trump's questionable claim that his ban was based on Obama administration decisions, Lewis said that the former president "fundamentally disagrees with the notion of discriminating against individuals because of their faith or religion."
On Capitol Hill, Democrats sought to capitalize on the growing public outcry and said they were hoping to pass legislation rescinding the ban and planning to delay confirmation votes for Trump's Cabinet nominees. Some Republicans have also spoken out against the ban, including Sens. Lindsey Graham and John McCain, top defense hawks who issued a joint statement bluntly worrying that the order could "become a self-inflicted wound in the fight against terrorism."
Criticism also emerged in other quarters. State Department diplomats have been circulating a document objecting to Trump's order since he announced it Friday. According to a draft version of the memo, first reported by the Lawfare blog, the dissenters say the ban will not deter attacks on American soil, but will generate ill will to U.S. citizens.
Iraqi parliament leaders called for retaliatory visa restrictions on American citizens, while a petition called on Britain to cancel Trump's state visit amid the furor.
In a statement, the United Nations High Commissioner for Refugees expressed concerns about "the uncertainty facing thousands of refugees around the world who are in the process of being resettled to the United States."
According to the agency, more than 800 refugees were set to go to America this week but are barred, and the 120-day halt on refugee resettlement could impact as many as 20,000 refugees.
"Refugees are anxious, confused and heartbroken at this suspension in what is already a lengthy process," the agency said.
In airports around the world, sorrow and relief mixed together as travelers entered an unknown future. Trump's virtually unprecedented executive action applies to migrants and U.S. legal residents from Iraq, Iran, Sudan, Somalia, Syria, Libya and Yemen, and to refugees from around the world. People subject to the ban include dual nationals born in one of the seven countries who also hold passports from U.S. allies such as the United Kingdom.
At Dulles International Airport, lawyers and Democratic members of congress had been unable to get information from Customs officials. Late Sunday, Rep. Bobby Scott, D-Va., said he was told there were no people in Customs custody at Dulles.
Dozens of demonstrators gathered at Dulles to welcome international visitors, along with volunteer lawyers gathered to monitor any potential problems.
Customs agents at Dulles forced lawful permanent U.S. residents to give up their green cards this weekend, according to a complaint filed Monday in Alexandria federal court. Tareq Aqel Mohammed Aziz and Ammar Aqel Mohammed Aziz were flying from Yemen to the U.S. Both had been granted immigrant visas because their father, who lives in Flint, Mich., is a U.S. citizen.
When they arrived at Dulles Saturday morning, the Aziz brothers were handcuffed and their immigration paperwork was seized, according to the complaint.
They were given documents to sign and allegedly told that if they did not, they would be removed from the U.S. and barred from coming back for five years. They were not allowed to see attorneys.
Under pressure, their attorneys say, they signed documents they did not understand, giving up their American visas, and agents stamped "cancelled" on those visas. Attorneys are asking for their visas to be returned, the forms they signed to be invalidated and for them to be returned to the United States.
Attorneys say about 50 to 60 other legal permanent residents were likewise tricked into giving up their status at Dulles. The lawyers say they hope to learn the identities of those individuals through the discovery process.
The Aziz brothers were compelled to buy tickets, at their own expense, for a flight back to Ethiopia, and when they arrived their passports were confiscated, leaving them in limbo.
Anthony Romero, executive director of the ACLU, said anyone with a valid visa should be able to enter the U.S., even if they are abroad, and the ACLU is working to investigate reports that is not happening.
In the long run, Romero said, ACLU lawyers will work to get the executive order thrown out permanently, and they will seek to have its implementation delayed while they press their case. This court battle could take years, he said.
Romero said they believe the executive order violates the Immigration and Nationality Act, some ratified treaties and - perhaps most acutely -- the First Amendment, because it seems to target Muslims. The order's exception for those from minority religions in majority Muslim countries "is clearly the smoking gun that this has targeted individuals of the Muslim faith."
"That dooms it from a first amendment perspective, in our view," Romero said.
The Council on American of Islamic Relations on Monday filed a sweeping challenge to the executive order, alleging its "purpose is to initiate the mass expulsion of immigrant and non-immigrant Muslims lawfully residing in the United States."
The lawsuit lists 27 plaintiffs, some of them activists and council officials and others students with visas, lawful permanent residents, refugees and others who allege Trump's order will deny them citizenship or prevent them from traveling abroad and returning home.
Among them is a doctor who the suit alleges is working in an underserved area in the United States.
"In the event he is prevented from returning to the United States, the area he serves will be lacking an essential physician to provide critical care to a substantial population in the United States," the lawsuit says.
Gadeir Abbas, who joined with others to file the suit, said the lawyers are "confident that we can win, and fortunately, President Trump and those around him make it very easy to reveal that bigotry. They can't keep their mouths shut."
Department of Homeland Security officials said the executive order does apply to green card holders, who may be let in to the country with a waiver. The directors of each large port of entry, such as airports, have the authority to determine on a case-by-case basis whether a green card holder may be let in.
Since Friday, dozens of green card holders at large airports in New York, Los Angeles and elsewhere have been admitted, officials said. The officials also said Friday's confusion has abated in these large airports because people subject to the ban are not being permitted to board flights overseas and so are not arriving at American airports.
In Seattle, two men whose visas were revoked and who were put on plane to be deported were allowed to enter the U.S. after a federal judge issued an emergency ruling in their favor, said Matt Adams, the men's lawyer.
Adams said the men - one an engineer from Sudan who was coming to the U.S. for a conference, the other a visitor from Yemen who was coming to see family - "literally had to get pulled off the plane as they were deporting them."
The men dropped their lawsuit after they were allowed to enter the U.S., Adams said.
"What we've seen is now with the national stay in effect, if anyone were to arrive, then the government's precluded from trying to immediately deport them like they were doing on Saturday," Adams said.
However, Adams said that more lawsuits were likely, noting the number of people getting stopped as they tried to board planes abroad.
The Department of Homeland Security noted that "less than one percent" of international air travelers arriving Saturday in the United States were "inconvenienced" by the executive order - though the situation described by lawyers and immigrant advocates across the country was one of widespread uncertainty and disorder at airports where travelers from the targeted countries were suddenly detained.
Trump wrote on Twitter that Homeland Security Secretary John F. Kelly "said that all is going well with very few problems. MAKE AMERICA SAFE AGAIN!" In other messages, Trump again cast his order as necessary to protect the country:
"There is nothing nice about searching for terrorists before they can enter our country. This was a big part of my campaign. Study the world!
"If the ban were announced with a one week notice, the "bad" would rush into our country during that week. A lot of bad 'dudes' out there!"
The seven countries under Trump's ban do not include several that have been tied to terrorists involved in major attacks or attempted plots in the United States.
White House officials through the weekend and Monday continued to justify the ban by citing the Sept. 11, 2001, attack, Boston Marathon bombing and San Bernardino, Calif., shooting rampage. None of these attacks involved people born in countries listed on the ban.
The Washington Post's Rachel Weiner, Ellen Nakashima, Juliet Eilperin and Carol Morello contributed to this report.