SEATTLE — Arriving at the United States border in Washington State early Sunday morning after a skiing trip to Canada, Negah Hekmati and her family were pulled out of line for further questioning by Customs and Border Protection agents.
The family found itself in a room filled with fellow Iranian-Americans, many of whom had already been held for hours. The agents wanted to know the identities of Ms. Hekmati’s parents, siblings, uncles and cousins. Her husband, a software engineer at Microsoft, was asked about any military service in his past. The agents left, and then came back with more questions.
During the five overnight hours they were held at the Peace Arch Border Crossing on their way back home to the Seattle area, Ms. Hekmati said, her 5-year-old would not sleep, worried about the prospect of jail. The young girl asked Ms. Hekmati to stop speaking Farsi, hoping that might help avoid further scrutiny.
“My kids shouldn’t experience such things,” Ms. Hekmati said. “They are U.S. citizens. This is not O.K.”
More than 100 people of Iranian descent appear to have faced similar delays at Washington’s border with Canada over the weekend, a process Gov. Jay Inslee described on Monday as the inappropriate “detention” of people — some of them United States citizens — who had done nothing wrong.
“I don’t think there’s any reason that is rational — and certainly constitutional — to target people based on the place of their birth,” Mr. Inslee said in an interview. “It’s pretty clear that that’s what they did here.”
The stepped-up border screenings came in the wake of an American drone strike on Friday that killed a powerful Iranian general, Qassim Suleimani, and spurred promises of revenge from Iran’s supreme leader.
Customs and Border Protection officials insisted that no one was detained or refused entry “because of their country of origin.” However, border agents often require people seeking admittance at the border to undergo a process known as secondary screening — which appears to have occurred in Washington, and in lesser numbers at other ports of entry.
An agency official told members of Congress on Monday that leaders in local offices had been “asked to remain vigilant and increase their situational awareness given the evolving threat environment.”
A half-dozen people of Iranian descent who were held for additional questioning in Washington described extensive questioning about their family and background, even though, like Ms. Hekmati, many were American citizens. One woman said she was asked to write down the name of the high school she graduated from in Iran 39 years ago. Another person was asked about his parents’ military service from before the 1979 Iranian Revolution. Others were asked to identify details about their Facebook accounts.
Representative Pramila Jayapal, Democrat of Washington, said she had heard that as many as 200 people of Iranian descent may have been affected.
Legal advocates at a Monday news conference in Seattle described several cases of travelers being questioned about their feelings about the United States and what was happening in Iran.
“United States citizens and legal permanent residents do not have to answer questions about their political views or religious views and practices, and cannot be denied entry into the United States for declining to answer these questions,” said Hina Shamsi, director of the American Civil Liberties Union’s National Security Project.
Ms. Shamsi said some of the questioning appeared to violate First Amendment rights. Under the law, she said, border agents who question citizens and legal permanent residents are permitted to verify only identity, legal status and whether a person is carrying contraband.
But she said the A.C.L.U. had for years tracked cases of invasive and sometimes unlawful questioning by border officers that went beyond those limits, into political and religious views and practices. She said she had seen such questions directed at Americans of Somali, Afghani and Pakistani backgrounds following military action in those countries.
“We see this at various points, especially when the U.S. takes some kind of conflict or warlike action abroad,” Ms. Shamsi said. “The deeply disturbing and painful reality for many people is that they then get treated like foreigners instead of the citizens that they are.”
While much of the additional border scrutiny of Iranian-Americans appears to have occurred on the Washington border, there were isolated reports of other concerning cases.
John Ghazvinian, a historian who specializes in the history of Iran’s relationship with the United States, said he was returning from a trip to Egypt through Kennedy International Airport in New York on Sunday when an officer asked him about his most recent travels to Iran. He was sent off for additional screening.
The questioning lasted only a few minutes and was courteous, Mr. Ghazvinian said, but the officer asked if he had close family in Iran and sought his opinion about the current situation in Iraq and Iran. He said it was possible the officer was making well-intentioned conversation, but he declined to answer given the context of the extra screening.
“I didn’t feel comfortable getting into it,” he said. “I said, ‘I don’t see how this is relevant.’” The officer returned his passport and allowed him to continue on his way.
Among those questioned at the Washington border was one woman who has lived in the United States for decades. She said in an interview that an officer asked whether she was part of any cult or Shiite Muslim organization.
Another traveler, Sepehr Ebrahimzadeh, said officers asked details about his father, who had performed military service before the Iranian Revolution.
Ms. Hekmati said one of the reasons she moved to the United States from Canada was the freedom offered in such a cultural melting pot. Now, she said, she is hearing from her friends in Canada who are wondering how much the United States really respects freedoms.
“This is very unfair to our community,” Ms. Hekmati said. “Just because we’re not complaining doesn’t mean we aren’t suffering.”
Mike Baker reported from Seattle, and Caitlin Dickerson from New York.