At one point, he said, a form used to abandon legal permanent residence was presented, and he was told he should relinquish his green card and instead apply for a work permit to enter the United States. He refused, was admitted into the country and is now back in New York. He described the experience as disheartening, saying it felt like he wasn’t welcome anymore.

The Department of Homeland Security did not respond to questions about the incident.

Another green card holder, Cliona Ward, 54, who has lived in Santa Cruz, Calif., since she was 12 years old, was detained at San Francisco International Airport on April 21 when she returned from a seven-day trip to Dublin. Ms. Ward had two felony convictions in 2007 and 2008 related to drug possession from a brief period of addiction she experienced, according to her sister, Orla Holladay.

According to Ms. Holladay, those convictions were expunged — meaning the conviction would be essentially removed from the criminal record — after Ms. Ward completed a rehabilitation program, and she has maintained her sobriety for almost 20 years. Her sister described her as a taxpayer who is in the country legally and is a part of the community.

Erin Hall, Ms. Ward’s lawyer, said that U.S. Immigration and Customs Enforcement, which handles such cases, has not provided any criminal records. The agency declined to comment.

Ms. Ward has been in detention for a week and has no date set for a hearing on her case.

What Travel Restrictions Has the United States Enacted?

As part of the Trump administration’s aggressive immigration agenda, border checkpoints have enacted what the White House refers to as “advanced vetting.” The measures, which include detaining and deporting tourists, have led allied countries, like Germany, to update travel advisories for their citizens about traveling to the United States