that included an attack on a military installation in Illinois, the Department of Justice said on Thursday.
The two Chicago-area men, both U.S. citizens, spoke of using army uniforms and military knowledge to get into an Illinois National Guard facility, the department said in a statement.
"Disturbingly, one of the defendants currently wears the same uniform of those they allegedly planned to attack," Assistant Attorney General John Carlin said in the statement.
Army National Guard Specialist Hasan Edmonds, 22, was arrested at Chicago Midway International Airport Wednesday night while attempting to fly to Cairo, the Justice Department said. His cousin, Jonas Edmonds, 29, was arrested at his Aurora, Illinois, home. Both arrests were made without incident.Both defendants met with an undercover Federal Bureau of Investigation employee and presented a plan to carry out an armed attack against a northern Illinois military facility where Hasan Edmonds had been training, the Justice Department said.
The plan was for Hasan Edmonds to join Islamic State fighters and Jonas Edmonds to attack the installation, according to an affidavit attached to the criminal complaint.
An undercover FBI employee sent a Facebook "friend" request in late 2014 to Hasan Edmonds, who replied in mid-January he was putting his affairs in order and gathering money for a trip.
In later messages Hasan Edmonds said it was his duty to support the Islamic State or be martyred trying and he did not intend to fulfill his last three years in the National Guard, the affidavit said.
"I'd rather struggle and strive hard in the cause of Allah rather than sit back and live a 'comfortable' life," Edmonds said in one message.
He said his cousin Jonas would seek martyrdom in the United States if a criminal conviction in Georgia prevented him from traveling abroad, the affidavit said.
Hasan and Jonas Edmonds met on Tuesday with an undercover FBI employee and discussed buying weapons and methods of attack on a drive to the installation, the affidavit said. Hasan Edmonds also described the installation and rooms to avoid.
Hasan Edmonds enlisted in the Illinois National Guard in August 2011, said Lieutenant Colonel Brad Leighton. Edmonds reported to the guard's Joliet base one weekend a month and annually did two weeks of active duty training.
If convicted, Hasan and Jonas Edmonds face a maximum penalty of 15 years in prison and a $250,000 fine.