CHICAGO (AP) — A former Sacramento, California, college student accused of attempting to provide material support to terrorists in Syria has invoked a rarely used argument in asking a federal judge to toss the case on grounds he qualifies for the kind of immunity commonly bestowed on national armies in wartime.

Lawyers for the 24-year-old Iraqi refugee, Aws Mohammed Younis Al-Jayab, argue in a motion filed late Tuesday in Chicago federal court that their client hooked up, not with terrorists, but with the sorts of Syrian rebels the U.S. government itself has backed in hopes of toppling the Bashar al-Assad regime.

The attorneys cite the internationally recognized "doctrine of combatant immunity" that prohibits the prosecution of soldiers involved in wars between nations. They say that that immunity — while geared toward armies — can be extended to rebels in conflicts, like Syria's, where multiple nations have intervened.

"The United States' support of ... rebels," the filing argues, "is evidence that it believed the belligerency against Assad was legitimate warfare and that fighters against Assad were entitled to combatant immunity for their legitimate acts of warfare against the regime."

Prosecutors in Chicago, where the case was transferred after Al-Jayab's 2016 arrest, have until Feb. 20 to file a response to the immunity claims. A spokesman for the U.S. attorney's office, Joseph Fitzpatrick, declined comment on the matter Wednesday.

Al-Jayab spent time in 2012 in a refugee camp near Damascus, Syria's capital, where friends and family members of his were killed by forces loyal to al-Assad, the defense filing says. That experience motivated him to return briefly to Syria in late 2013 to fight, his lawyers say.

Al-Jayab migrated to the U.S. in 2012. He flew to Turkey after boarding a plane at Chicago O'Hare International Airport in 2013 and then traveled to Syria, including Aleppo. He returned to the U.S. in 2014 and settled in California, where he enrolled in computer courses at a community college.

In Syria, Al-Jayab associated with a group called Ansar al-Sham, which, unlike Islamic State, has not been designated a terrorist group by the State Department, the new filings say. Earlier government filings dispute that, linking Al-Jayab to Ansar al-Islam and the al-Nusra Front, both of which are designated as terrorist groups.

Al-Jayab has pleaded not guilty. If convicted, he faces a maximum 15 years in prison on the material-support charge.

___

Follow Michael Tarm on Twitter at https://twitter.com/mtarm