A US teenager has been arrested on terrorism-related charges and accused of seeking to join an al-Qaeda-affiliated group in war-torn Syria, the FBI says.
Abdella Ahmad Tounisi, 18, was arrested on Friday night as he attempted to board a flight from Chicago's O'Hare International Airport to Turkey, which borders Syria, the FBI said.
The head of the FBI office in Chicago, Cory B Nelson, said in a statement announcing the arrest that there are no links between Tounisi's case and the bombings at the Boston Marathon earlier in the week.
Tounisi, a US citizen, is charged with one count of attempting to provide material support to a foreign terrorist organisation. If convicted, he faces a maximum 15-year prison term.
Tounisi carried out research online about Jabhat al-Nusrah, or Nursa Front, which is a well-organised rebel faction fighting Syrian President Bashar Assad's regime in a bloody civil war, the complaint says.
The US government has designated the group a foreign terrorist organisation, describing it as an alias for the group al-Qaeda in Iraq.
Neither the complaint nor the FBI statement includes the name of a lawyer for Tounisi.
According to the FBI, Tounisi made contact over email last month with an FBI employee posing as a Nursa Front recruiter and expressed "his willingness to die for the cause."
The complaint also says Tounisi is a friend of Adel Daoud, another Chicago-area man who was arrested last year on charges he sought to detonate a device he thought was a bomb outside a downtown bar.
Daoud has pleaded not guilty and is in jail awaiting trial.
The complaint does not accuse Tounisi of playing a role in the alleged attack planned by Daoud, though it does say the two friends discussed "techniques and targets" before Daoud's arrest.
