Feds: Teen Arrested at O’Hare, Wanted to Join ISIS 19-year-old charged with attempting to provide material support to terror group.

 -- An Illinois teenager was arrested Saturday at a major airport as authorities say he was attempting to travel to the Middle East to join the Islamic State of Iraq and Syria (ISIS).

Mohammed Hamzah Khan, a 19-year-old U.S. citizen from Bolingbrook, appeared in court today to face charges for allegedly attempting to provide material support for a terrorist organization. If convicted, Khan could face up to 15 years in prison.

Federal authorities said Khan was arrested Saturday at Chicago’s O’Hare airport by members of the FBI’s Chicago Join Terrorism Task Force. In court today it was revealed he had purchased a ticket to Istanbul, via Vienna. Investigators allege he planned to slip through the porous Turkish border to Syria or on to Iraq.

Digital Feature: What Is ISIS?

American Aid Worker Kassig in ISIS Video 'Scared to Die'

ISIS Appears to Behead British Captive Alan Henning

In a criminal complaint, prosecutors said Khan had apparently penned a letter to his family, to be found in his bedroom after he left the country.

“My dear parents, there are a number of reasons I will be going to the blessed land of Shaam [Syria] and leaving my home,” the letter says, according to the complaint. Among other things, the letter said, “We are all witness that the western societies are getting more immoral day by day. I do not want my kids being exposed to filth like this.”

Khan purportedly asked them not to contact the authorities and instead invited them to join him in the Middle East.

The man's parents, who were present in court, declined to comment on the case.

Top U.S. security officials have estimated that around 100 Americans have traveled to the Middle East to take part in the conflict in Syria and Iraq with various militant groups, including ISIS.