When his London-to-Washington flight was unexpectedly diverted to another city, it didn't occur to the singer once known as Cat Stevens that he was the problem. And when it finally did, he suddenly felt very vulnerable.
"I was literally cut off from my family, from my daughter. I was in the dark," the musician, now known as Yusuf Islam, told ABC News' Elizabeth Vargas.
Islam — who changed his name from Cat Stevens after he converted to Islam in the 1970s — was barred from entering the United States after his name was discovered on a U.S. government "no-fly" list on Sept. 21.
He said United Airlines' Flight 919 — from London to Washington's Dulles International Airport — seemed routine until he heard an announcement over the loudspeaker stating the plane would be landing in a different location. There were 249 passengers on board, and it never crossed Islam's mind that he might be the problem.
The flight had been diverted to Maine's Bangor International Airport, where federal agents were waiting.
"The door opened and in walked six gigantically tall, you know, uniformed officers, and they kind of came to me directly, and said, 'Are you Yusuf Islam?' And I thought, what is going on?" Islam said.
"They took me to the immigration office there. Then I got interviewed by some FBI agents, and that was like the beginning of what I began to realize was a terrible ordeal which I was about to go through," he said.
Islam, 56, said he was traveling to the United States with his 21-year-old daughter to record some music in Nashville, Tenn.
Now he wants to know why he's no longer allowed in the country where he had been welcome for so many years.
Islam says he didn't learn much from the questions he was asked by federal agents and said the questions seemed to revolve mostly around his Muslim name.
"Well, kind of how to spell my name, and they kept on repeating that question actually and saying, 'Are you sure you don't spell it Y-O-U-S?'
I said, 'no, I spell it Y-U-S-U-F' so I thought at one point, well hang on, they've probably got me wrong, mixed up with somebody else," Islam said.
"The questioning, you know, was just so strange and I just didn't know what was happening," he said.
Homeland Security spokesman Brian Doyle said only that Islam is on the no-fly list because the intelligence community has recently obtained information that "further heightens concern" about the folk singer.
"Yusuf Islam has been placed on the watch lists because of activities that could potentially be related to terrorism," Doyle said. "It's a serious matter."
Islam says he still doesn't understand why his new name has been linked to terrorism. In a statement, Islam says he's "initiated a legal process" to try to find out exactly why he was put on the list and removed from the flight.
United and the U.S. government have said that they're working to figure out why Islam was allowed to board the flight in the first place. Homeland Security officials have said they're looking at the possibility that Islam's name was spelled differently on the no-fly list.
Under rules imposed following the Sept. 11, 2001, attacks, once an international flight is bound for the United States, passenger information is forwarded to U.S. officials. The information is used to run a more thorough check against government watch lists. Authorities discovered Islam was on Flight 919 after receiving the passenger information from United.
Islam was born Stephen Georgiou in London. He took Cat Stevens as a stage name and had a string of 11 Top 40 hits, including "Wild World," "Morning Has Broken," and "Peace Train," in the 1960s and '70s. He also earned eight gold albums during his pop career.
But in 1979, at the height of his fame, the singer walked away from the spotlight. He converted from Greek Orthodox to Islam. And, most shocking to his fans, he quit the music business. After his conversion, he entered into an arranged marriage, living a quiet private life and fathering five children.
The next time he garnered major media attention was during a controversy in 1989, when he appeared to support an edict of death issued by Ayatollah Ruhollah Khomeini of Iran against author Salman Rushdie for his alleged defamation of the prophet Muhammad.
For the next decade he spent most of his time raising money for various Muslim-related charities.
In recent years, as radical fundamentalism has become a dominant force in Islam, the former pop star has emerged as a face of moderation in the faith. After the Sept. 11, 2001, terrorist attacks, he wrote an editorial saying that Islam had been hijacked by terrorists. He told Vargas he felt it was "absolutely imperative that people get to know the real Islam … when something is wrong it's wrong, you know it's totally abhorrent and we totally condemn it.
He also condemned the recent deadly siege of school in Breslen, Russia, by Islamic militants. "The Breslen tragedy was so sickening," Islam told Vargas. "Every Muslim I ever met was so sickened by what was happening, and so again we spoke out. We condemned it," he said.
He has also appealed to extremists in Iraq to free British hostage Kenneth Bigley.
"My whole aim," Islam said, "in whatever I say, whatever I do, is to follow the peaceful line of having people live together. … If we can all play in that game, the world will be a better place."
But there are some who still doubt him — most notably U.S. government officials, who stand by their decision to keep Islam on the "no-fly" list.
Although the government refused to provide any specifics, officials suggest that Islam's charitable contributions may have ended up funding terrorist groups, in particular, Hamas, which has claimed responsibility for some of the most notorious suicide bombings in Israel.
Islam has twice been denied entry into Israel, and the Israeli government told 20/20 earlier this week that it has proof charities he has supported continue to be used to launder money for Hamas. But Islam says he has never knowingly given money to Hamas. "The first time this accusation came up," he said, "I didn't even know what this organization was … Nobody I've ever met has said, 'I'm from Hamas.' "
His critics, however, point to a 1998 event in which Islam was helping to raise money for a Canadian charity. According to a report prepared for the Canadian government in 2000, the group was described as a "Hamas front group … that has unsavory links with terrorism."
Islam says he has tried to be a bridge-builder, making people in the West more familiar with the Islamic faith. He has recently begun trying to build a bridge with his own past.
In Vargas' 2000 interview with Islam, he said he hadn't picked up a guitar since his religious conversion. But he said he has recently begun playing again. "My son's got a guitar and I have played a few things and you know what? It sounds very good," he said.
He said he has written some new pieces, and doesn't want to "harp on the old songs, because I think there are some interesting and important things to say now."
But if Islam returns to the music scene, the question remains unanswered at this point whether he'll be able to return to the United States.