A complaint outlining the charges against Bradley and Muthana does not mention the defendants discussing their intentions with IS or others beyond the two undercover law enforcement officers.
Bradley sought transit to the Middle East by cargo ship because he feared he might have been on a terrorist watch list, prosecutors said.
In 2019, Bradley planned to travel to Afghanistan to join the Taliban and attack American soldiers but changed his mind because of ideological differences with the person he was supposed to travel with, a person who was subsequently arrested, prosecutors said, citing an FBI interview at the time.
Muthana, of Alabama, also expressed support for IS and discussed with Bradley plans to travel together to the Middle East to fight on behalf of the group, prosecutors said. After her arrest, she waived her right to remain silent and said she was willing to fight and kill Americans, prosecutors said.
A U.S.-led coalition captured the last of the territory held by the Islamic State group about two years ago, ending its self-declared caliphate that covered large parts of Iraq and Syria. Since then, remaining IS militants have gone underground in the Syrian-Iraqi border region, continuing an insurgency.
Muthana and Bradley were married in January.
After traveling to Alabama to visit Muthana, prosecutors said, Bradley approached the undercover officer with the idea of traveling on a cargo ship to join IS. The officer connected Bradley with a "facilitator" — another undercover officer — and Bradley paid that person $1,000 in cash for travel costs, prosecutors said.
Bradley told that officer that he and Muthana planned to be "fighting" upon arrival Yemen and that he'd had a dream that he had given an oath of allegiance to IS leader Abu Ibrahim al-Hashimi al-Qurayshi prosecutors said.