A Northern Virginia teenager who had been barred from flying home from Kuwait landed in Washington on Friday morning, four weeks after being detained, allegedly beaten by Kuwait authorities and questioned by FBI agents about possible terrorist connections.

Gulet Mohamed, dressed in a worn hooded sweat shirt and sweat pants, was embraced by his family after he arrived at Washington Dulles International Airport, the end of an ordeal that he said had "made me stronger."

The United States "is built upon fighting for your rights," Mohamed, 19, said in an interview.

Civil liberties groups charge that his case is the latest episode in which the U.S. government has temporarily exiled U.S. citizens or legal residents so they can be questioned about possible terrorist links without legal counsel.

The American Civil Liberties Union is suing the U.S. government on behalf of 17 citizens or legal residents who were not allowed to board flights to, from or within the United States, presumably because, like Mohamed, they were on the government's no-fly list. Of those stranded overseas, all were eventually told they could return, often after they agreed to speak to the FBI. None was arrested upon their return.

The ACLU suit, filed in Portland, Ore., alleges that Americans placed on the no-fly list are denied due process because there is no effective way to challenge their inclusion. The government does not acknowledge that any particular individual is on the no-fly list or its other watch lists. Nor will it reveal the exact criteria it uses to place people on its list.

There are about 10,000 people on the no-fly list, whose size fluctuates depending on the threat level, and up to 500 of those are U.S. citizens, according to a U.S. counter-terrorism official.

The FBI has declined to discuss Mohamed's case. But U.S. officials insist that the process used to place individuals on the no-fly list is legal and well founded, and relies on credible intelligence.

Many individuals represented by the ACLU had been out of the country for an extended period and had traveled to Yemen, a major focus of U.S. counterterrorism efforts after several plots targeting Americans originated there.

Mohamed said he left Northern Virginia in March 2009, traveling first to Yemen, where he stayed for three weeks before moving on, at his mother's request, to stay with relatives in a relatively peaceful region of Somalia. He said he went abroad to study Islam, Arabic and to get in touch with his roots.

In August 2009, Mohamed said he went to Kuwait, where another relative lives, to continue his studies. Last month, while at the airport to renew his visa, he was detained by two men. Once in the back seat of a car and blindfolded, he said, he burst into tears.

"I felt like I was getting kidnapped," said Mohamed, speaking at his home in the Alexandria section of Fairfax County.

Mohamed said that he was taken to a jail and that his interrogators asked him whether he knew Anwar al-Aulaqi, the U.S.-born cleric involved with an al-Qaeda affiliate in Yemen, or Osama bin Laden. He said the Kuwaitis insisted that he knew Aulaqi when the cleric preached at a Falls Church mosque in 2001.

"I told them he was the imam in 2001. I was in fourth or fifth grade. I was a little kid," Mohamed said. "If I went there, I don't remember him. They told me: 'You're lying.' "

Over the next several days, Mohamed said he was interrogated for 12 hours a day, slapped, beaten with sticks and threatened with electrocution. He said his interrogators demanded his e-mail and Facebook passwords, which he gave them, and took his iPhone.

After a week, Mohamed said he was taken to a deportation facility where he was visited by three FBI agents. He said they asked him why he went to Yemen and Somalia, saying his travels "raised red flags." He said he refused to talk to them without a lawyer present.

A State Department spokesman said the U.S. government had no role in Mohamed's initial detention. The Kuwaiti Embassy in Washington did not respond to a request for comment.

During a second visit to the detention center, Mohamed said, the FBI agents suggested that he had joined terrorist camps in Somalia and Yemen but that, perhaps, he was now a "changed man." They asked him to become an informant for the bureau, an offer he declined, he said.

He said his plans are to attend George Mason University and study information technology.

His family said they have been shaken by the experience. "We did not expect this from America," said his brother, Leeban Mohamed, 24. "We've seen America change."

The no-fly list is maintained by the Terrorist Screening Center, which is overseen by the FBI. In a redacted submission to the court in Portland, Christopher M. Piehota, deputy director for operations, said the TSC receives information about suspected domestic and international terrorists from the FBI and the National Counterterrorism Center.

To make the general database, there must be a "reasonable suspicion to believe that a person is a known or suspected terrorist," the government said in court papers. To be placed on the no-fly list "additional derogatory information must exist demonstrating that the individual meets the requisite criteria."

On Friday, a federal judge continued a hearing on a government motion asking her to dismiss the ACLU complaint, saying she wanted further briefings.

Staff writer Tara Bahrampour and staff researcher Julie Tate contributed to this report.