An Illinois teenager was busted for trying to leave the country to join Islamic State fighters and their terroristic campaign in Syria, federal officials revealed Friday.

Mohammed Hamzah Khan, 19, was caught Saturday at O'Hare International Airport before he got on a flight to Turkey, which shares a border with Syria, according to a criminal complaint obtained by the Associate Press. 

The teen, from Chicago's Bolingbrook suburb, was charged with attempting to provide material support to a foreign terrorist group.

It was not immediately clear why Khan was targeted at the airport. According to a letter he wrote his parents, Khan was fed up with Western society and wanted to join the Sunni jihadists' cause.

"We are all witness that the Western societies are getting more immoral day by day," reads the three-page letter, according to the complaint. "I do not want my kids being exposed to filth like this."

Khan asked his parents to join him in the "Islamic State" and signed the letter "Your loving son," according to the complaint. He also allegedly begged his parents not to tell the police about his plan.

Federal agents executed a search warrant and found the letter in the teen's bedroom while he was detained at the airport, CNN reported. He made it just past airport security when agents stopped him.

FBI officials believe about a dozen U.S. citizens are in Syria fighting with the Islamist extremists as they commit atrocities across the country and Iraq in the name of establishing a caliphate, the AP reported.

Upon questioning, Khan reportedly told agents he was in contact with someone online who gave him the number of a source in Istanbul who would lead him to the militants, the AP reported. Officials did not say who purchased the round-trip ticket from Chicago to Istanbul, according to CNN.

Once with the militants, Khan said he wanted to "be involved in some type of public service, a police force, humanitarian work or a combat role," Khan said according to the criminal complaint.

The teen's parents did not offer comment as their son was arraigned in court on Monday. He faces up to 15 years in prison if convicted.