Ali Charaf Damache, 52, has been wanted in the United States for years on charges that he conspired with an American woman known as "Jihad Jane" to recruit people online to carry out attacks in Europe and South Asia.
The suspect -- who was also known by the online username "Theblackflag" -- made an initial appearance before a federal magistrate judge in Philadelphia on Friday, said officials in the eastern district of Pennsylvania.
He is scheduled to attend a bail hearing and arraignment on August 28, a spokeswoman for the district said.
US officials say Damache worked with Colleen LaRose -- a Pennsylvania woman who converted to Islam and took the name Jihad Jane -- and others to create a "violent jihad organization" with men and women from Europe and the United States.
LaRose was jailed for 10 years in 2014 for plotting attacks, including the murder of Swedish artist Lars Vilks, who has survived several death threats since penning a cartoon portraying the Prophet Mohammed as a dog.
US authorities say Damache and others recruited men online "to wage violent jihad in South Asia and Europe" as well as women with passports and the ability to travel to and around Europe in support of their plots.
Damache had contested his extradition. He was initially detained in Ireland, but a court there refused a US request to extradite him and he walked free.
He was re-arrested in December 2015 in Barcelona and the Spanish government approved the US extradition request in February 2016.
He faces up to 45 years in an American prison if convicted.
He was the first foreigner brought to the United States to face terrorism charges under Trump, who has said it would be "fine" to send suspects to the military prison in Guantanamo Bay rather than civilian courtrooms as under Barack Obama.
The move was welcomed by the American Civil Liberties Union, which has bitterly opposed the Trump administration on a slew of issues.
"Prosecuting terrorism cases in federal courts is the right thing to do," said David Cole, ACLU's national legal director. "The alternatives of indefinite detention at Guantanamo, and flawed military commissions violate basic constitutional and human rights, and have created far more problems than they've solved."