An Illinois Army National Guard soldier and his cousin will plead guilty next month to charges they conspired to provide material support to the Islamic State group.

An attorney for Hasan Edmonds and Jonas Edmonds said during a court hearing Thursday his clients are working on written plea agreements with prosecutors.

The Aurora men are accused of plotting to attack the Joliet Armory with assault rifles and grenades.

Prosecutors said that Jonas Edmonds will plead guilty on Dec. 9 and guardsman Hasan Edmonds will plead guilty Dec. 14.

Prosecutors have alleged that Jonas Edmonds planned to wear his cousin's military uniform in the attack at the facility where Hasan Edmonds trained, and that they hoped to kill as many as 150 people.

Both men are being held without bond.