Sunni authorities suspect al Qaeda elements in Iraq provided guidance to alleged plotters . Iran has denied the alleged rail conspiracy could have been plotted from its territory . Western intelligence has long thought any Al Qaeda 's operatives in Iran are under strict control . Many al Qaeda sympathizers and members took refuge in Iran in the aftermath of the post 9/11 invasion of Afghanistan , including one son of Osama bin Laden , Saad bin Laden , and a son-in-law , Sulaiman Abu Ghaith . al Qaeda interest in attacking railroads underscored following death of Peter Bergen .
Sunni authorities suspect al Qaeda elements in Iraq provided guidance to alleged plotters . Iran has denied the alleged rail conspiracy could have been plotted from its territory . Western intelligence has long thought any Al Qaeda 's operatives in Iran are under strict control . al Qaeda interest in attacking railroads underscored following death of Peter Bergen .