Mr Khalid and Mr Damache allegedly recruited and
organised with LaRose (pictured) entirely online
The US has officially charged two men of conspiring with a woman known as "Jihad Jane" to recruit women and solicit funds for terror plots.
One of the two charged is Mohammad Hassan Khalid, 18, a Pakistani immigrant from the state of Maryland reported to have won a full scholarship to Johns Hopkins University.
Ali Charaf Damache, 46, an Algerian living in Ireland, was also charged.
Prosecutors said the US would ask Ireland to extradite Mr Damache.
Colleen LaRose, known by the internet pseudonym "Jihad Jane," admitted in February to plotting to kill Swedish cartoonist Lars Vilks, who drew pictures of the Prophet Muhammad with the body of a dog.
She faces a possible life sentence after pleading guilty to four federal charges, including conspiracy to support terrorists. She has not yet been sentenced.
Mr Damache faces up to 45 years in prison if convicted, while Mr Khalid could a 15-year term.
Mr Khalid met LaRose in an online chat room in 2009, when he was just 15, according to the indictment.
"This case demonstrates that we must remain vigilant within our communities to make sure that we bring to justice those terrorists, of any age or background, who seek to do great harm to our citizens," said US Attorney Zane Memeger in a statement.