Khweis was tasked with running errands such as grocery shopping, taking out the trash at his Islamic State house and caring for wounded fighters.
He eventually became "frustrated with waiting" for military training, according to an FBI special agent who testified during Khweis' trial.
"Many of the Americans had little to no combat experience and were assigned duties such as cleaning safe houses, cooking, and caring for the sick and injured," the report states.
"This was hardly the glamorous experience they anticipated, and some sought a way back to the comforts of home.".
The Americans who went overseas tended to be male, with an average age of 27, according to the report.
In high-profile case after high-profile case, U.S. officials have determined that attackers radicalized in the United States after consuming online propaganda.
"The risk that 'homegrown' extremists will commit attacks on U.S. soil outweighs the risk of attacks from returning travelers," the authors wrote. »