Nineteen-year-old Illinois resident Mohammed Hamzah Khan was arrested by the FBI at Chicago’s O’Hare Airport on Saturday, with the feds accusing the teenager of plotting to join Islamic State jihadists in Syria.

Khan appeared in court on Monday, where he was accused of attempting to provide material support for a terrorist organization, which carries a maximum penalty of 15 years.

Agents from Chicago’s Joint Terrorism Task Force detained Khan before he could board a flight to Istanbul. Authorities claim Khan’s plan was to infiltrate Syria through the Turkish border and then attempt to join up with Islamic State forces battling the Syrian regime, other Islamic rebels, and Kurdish fighters in that country.

Khan left a note in his bedroom for his parents to find after he fled the country. “My dear parents, there are a number of reasons I will be going to the blessed land of Shaam [Greater Syria] and leaving my home,” he wrote. “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.”

The U.S. government estimates that around 100 Americans are currently fighting with the Islamic State in Iraq and Syria — a number dwarfed by the thousands of European Muslims who have joined the terrorist organization.