TOM HAYS, Associated Press

NEWY YORK (AP) — U.S. authorities are intensifying their efforts to identify and neutralize Islamic State sympathizers they believe could pose a terror threat on American soil.

That concern was demonstrated this month with the arrest of Donald Ray Morgan when he returned from Lebanon at New York's Kennedy Airport.

The FBI had been monitoring tweets by the North Carolina man praising extremists fighting in Syria and Iraq. An FBI agent testified at a court hearing that Morgan denied trying to join the group and or knowing if any of the fighters had left the region and returned to the U.S.

Federal and NYPD officials have estimated that at least 100 Americans could be fighting with the Sunni extremists.

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