A US soldier and his cousin have been arrested and charged with conspiring to support the Islamic State, the Department of Justice has said.
The National Guard soldier, 22, and the other man allegedly discussed using army uniforms and military access to attack an Illinois military facility.
The soldier also planned to travel to the Middle East to fight with the Islamic State, say prosecutors.
Both men have been charged with trying to provide support to a terror group.
The FBI arrested the soldier at Chicago Midway International Airport on Wednesday as he attempted to fly to Cairo, and arrested his 29-year-old cousin at his suburban home on the same day.
Both men have been charged with one count of conspiring to provide material support and resources to a foreign terrorist organisation.
They face up to 15 years in prison and a fine of up to $250,000 (£167,800), if found guilty.
Army National Guard Specialist Hasan Edmonds first came to the attention of the FBI in 2014, the Justice Department said in a statement.
Investigators allege that he and Jonas Edmonds, his cousin, had plotted for Hasan Edmonds to travel overseas with a view to fight on behalf of the Islamic State.
The pair also planned for Jonas Edmonds to carry out an attack against a military facility in northern Illinois, where Hasan Edmonds had been training.
The cousins revealed their plot to an undercover FBI agent, and said they would use Hadan Edmonds’ military uniform to gain access to the facility.
What is the US Army National Guard?
- each US state, district, and territory has a national guard
- state governors serve as commander-in-chief, but the US president can deploy them to assist national forces
- often called “citizen soldiers”, they maintain civilian jobs and usually train for one weekend each month plus one longer multi-week training session each year
- usually deployed to deal with civil emergencies or natural disasters, but many have been deployed overseas – especially in Iraq
“Disturbingly, one of the defendants currently wears the same uniform of those they allegedly planned to attack,” Assistant Attorney General John Carlin said.
Hasan Edmonds booked tickets to depart from Chicago on Wednesday and would have arrived in Cairo on Thursday, after taking connecting flights in Detroit and Amsterdam.
They are set to appear in court for the first time at 15:00 local time (20:00 GMT).