CHICAGO (CBS) — A Bolingbrook teen pleaded guilty Thursday to charges that he tried to join Islamic State terrorists in Syria.

Mohammed Hamzah Khan entered the plea to one count of attempting to provide material support to a foreign terrorist organization.

The organization is identified in the plea agreement as ISIL.

He faces a maximum sentence of 15 years in prison.

Khan was arrested in October at O’Hare Airport as he tried to travel to the Middle East with two younger siblings.

At a hearing in January, Khan’s attorney, Thomas Durkin, said his client appeared to have fallen under the influence of Islamic State propaganda. But he has also described the government’s case as weak.

In April, Durkin said the irrationality the 19-year-old displayed in assessing Islamic State is a feature of his age group.

He said that “doesn’t make them crazy, it just makes them teenagers.”