An elite Iranian military unit and a terrorist group backed by Iran are stepping up their efforts to attack Western targets.
According to a report from the Washington Institute for Near East Studies, the Lebanese militant group Hezbollah and Iran's Quds force are a growing threat.
The report says between May 2011 and July 2012 the two groups plotted more than 20 terror attacks together and independently.
Only one of those attacks succeeded, but the report's author Matthew Levitt concluded the groups are learning from their mistakes and improving their effectiveness.
"What is particularly striking is how amateurish the actions of both organizations have been: Targets were poorly chosen and assaults carried out with gross incompetence," Levitt said in the report.
"But as the groups brush off the cobwebs and professionalize their operations, this sloppy tradecraft could quickly be replaced by operational success."