An American and a Filipino national face life in prison after being found guilty in the US of plotting to aid jihadists overseas and to kill US soldiers.
A jury convicted Sohiel Omar Kabir, 36, a naturalised US citizen, and Filipino Ralph Deleon, 25, on Thursday at the conclusion of a six-week trial that comes as the US leads air strikes in Syria and Iraq against Islamic militants.
The trial, in California, underlined the threat that homegrown extremists pose to the United States.
Deleon was specifically found guilty of conspiring to provide material support to Al-Qaeda, to receive military-type training from the group and to commit murder, kidnapping, or maiming overseas.
"This case shows that the appeal of extremist ideologies can reach from Afghanistan to America," said US Attorney Stephanie Yonekura after the trial.
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This demonstrated "the clear need for continued vigilance in rooting out homegrown violent extremists who plot terrorist acts both here and abroad".
Two co-conspirators - Miguel Alejandro Santana Vidriales and Arifeen David Gojali - had already pleaded guilty and are awaiting sentencing.
The trial heard evidence that Kabir traveled to Afghanistan in 2012 and encouraged Santana and Deleon to come with him, saying they would all join "the students" - Taliban militants - and "the professors" - Al-Qaeda.
An undercover FBI agent contacted Santana and Deleon. The latter said he wanted to go abroad to wage "violent jihad," while Santana said he wanted to be a sniper.
In September 2012, Deleon and Santana recruited Gojali to accompany them to Afghanistan.
The three undertook preliminary training in southern California at firearms and paintball facilities.
The trio were arrested in November that year as they prepared to drive south to Mexico, en route to Afghanistan.
Judge Virginia A Phillips will hand down sentences on February 23.
