The man removed from an Aeromexico flight bound for Mexico City Sunday was the subject of a terror warning issued for the U.S.-Mexico border last week, senior U.S. counterterrorism officials told NBC News on Monday.
Homeland Security had asked law enforcement in Houston to be on the lookout for a suspected member of al-Shabaab, an al-Qaida ally based in Somalia, early last week, the sources said.
The man was thought to be headed for the United States via Mexico.
On Sunday, an Aeromexico flight from Paris was diverted to Montreal, where the man was detained.
Canadian authorities on Monday identified the man as Abdirahman Ali Gaall and that he would have his first court hearing on Wednesday.
Gaall is a Somali national but holds resident status in the United States, the counterterrorism sources said. His wife is an American citizen, said one official. He did not have the couple's address in the United States.
The Canada Border Services Agency confirmed Monday that Gaall was on a U.S. no-fly list and said the man was known to them.
Other passengers on Aeromexico Flight 006 from Charles De Gaulle Airport to Mexico City were re-screened and allowed to re-board the flight.
'He was calm'
Passengers coming off the plane told The Associated Press that six Canadian police officers had boarded in Montreal, handcuffed the man and led him off the aircraft. They said the man did not resist.
"He was calm as if he knew what was going to happen," said Mauricio Oliver, a 36-year-old Mexican passenger. "They handcuffed him and they took him."
Oliver said a flight attendant told him the man was from Somalia, but other passengers gave conflicting information about his nationality.
French passenger Christian Collier, 63, said everyone aboard remained calm during the incident.
A spokesman for Canada Border Services, Dominque McNeely, said there was no incident on the aircraft and that law-enforcement officials boarded the plane around 2:30 p.m. local time Sunday and took the suspect into custody.
"The flight landed and we had excellent cooperation with everyone involved," he said.