This is probably not a precedent that the Obama administration wants to make; to associate autonomous radical Islamists with Piracy.
For centuries, international laws allowed for pirates captured in battle to be summarily executed (or ‘drawn and quartered’ in England). Like al-Qaeda, Pirates represented no national interest. They were just a gang of guys with a common cause.
Are radical Islamists the land equivalent of piracy on the high seas?
Many on the left are hung up on the notion that an act of war can only be caused by one officially recognized nation onto another. This is their justification for trying radical Islamists in civilian court.
The United States HAS officially declared war on autonomous groups of pirates before. (see: The Barbary Wars) Those were MUSLIM pirates, as well.