article_snippet: an adult is believed to have joined ISIS there, a separate law enforcement official said.
article_snippet: More than 20,000 foreigners have gone to fight for ISIS, the radical Islamist group that controls portions of Iraq and Syria, experts have told Congress.
article_snippet: National Intelligence Director James Clapper said 180 Americans have tried to go to fight in Syria.
article_snippet: It's unclear how many of those were attempting to join ISIS.
article_snippet: Who has been recruited to ISIS from the West .
article_snippet: Others have been prevented from going there or providing support.
article_snippet: Three Denver teenagers, who investigators say were recruited via social media, were stopped in Germany in October and sent back to the United States.