Although the United States had suffered Jihadist violence on its own territory as far back as the early 1990s, many commentators still saw 9/11 as the first instance of Islamist terrorism inside the United States.
In the early days of the Obama administration, US security commentators appeared to switch emphasis from seeing the main threat as Al Qaeda or related individuals from the Middle East or Af-Pak, but - bizarrely enough - the UK. By this they meant British Muslims, with easy understanding of America's culture and few barriers on getting into the US, who were attempting or planning attacks in the country. Richard Reid and Dhiren Barot being two prominent examples. Such claims turn conventional security policy and indeed theories of international relations on their head - that at the same time one nation could be the greatest supporter of another, and at the same time pose the biggest threat to it.
This evening Radio 4's "American Jihad" documentary suggests that the emphasis has now switched again, to what may well be called the British Model - of domestic terrorism from home grown actors, often first or second generation Muslims, who have adopted Jihadi beliefs and practices. American Jihad is at 8pm this evening on Radio 4, and is repeated on Sunday at 5pm. An accompanying BBC article can be read here.