US teen charged with 'trying to join IS'

Zarine Kahn (R) and Shafi Ullah Khan (C), the parents of Mohammed Hamzah Khan, 19, listen as Thomas Anthony Durkin, the attorney for their son, talks to reporters after a bond hearing on October 9, 2014 in Chicago, Illinois (AFP Photo/Brian Kersey)

Washington (AFP) - A US teen arrested at a Chicago airport while allegedly trying to join up with Islamic State fighters in Iraq and Syria, has been formally charged, federal prosecutors said Friday.

Mohammed Hamzah Khan, 19, faces one count of "attempting to provide material support to a foreign terrorist organization," which carries a maximum penalty of up to 15 years in prison and a $250,000 fine.

No date has yet been set for Khan's next court appearance, according to the statement from the Justice Department, which added that the investigation is continuing.

The Illinois teenager was arrested October 4 at Chicago's O'Hare airport with a roundtrip ticket to Istanbul.

Law enforcement agents who searched Khan's suburban Chicago home said they had found multiple handwritten letters by Khan and others.

The letters expressed support for the IS group and made reference to jihad, authorities said.

The Central Intelligence Agency estimated last year there were around 15,000 foreigners fighting with the Islamic State and other hardcore militant groups.

Experts say most come from Muslim countries, but there are also hundreds from Europe or the United States.

Officials worry some will return battle-hardened and ready to launch attacks in their home countries.