Alexander Justin White allegedly began posting his support for ISIS on social media.
In a recording released days after he was reported to be wounded in an airstrike, the leader of the Islamic State group said the U.S.-led coalition's campaign had failed and it would eventually have to send ground troops into battle.
Militants of the Islamic State group were closing in Monday on a Kurdish area of Syria on the border with Turkey - an advance unhindered so far by U.S.-led coalition airstrikes, including one that struck a grain silo, killing two civilians, according to activists.
