In a commentary on Bush's speech released by the Washington-based Center for Strategic and International Studies (CSIS), Anthony Cordesman, a former director of intelligence assessment in the office of the US secretary of defence, described as a key flaw Bush's “effort to explain the insurgency in Iraq almost solely in terms of foreign Islamic extremists”.
Cordesman argued that while Bush “correctly referred to hundreds of foreign fighters, their horrifying extremism, and the very real threat they post”, he “totally failed to mention the thousands of native Iraqis that make up the core of the insurgency,
the fact we have only some 600 foreign detainees out a total of 14,000 (detainees), the fact most intelligence estimates put foreign fighters at around 5% of the total, and the fact we face a major native popular Sunni uprising and deep Sunni distrust.”
http://www.greenleft.org.au/back/2005/634/634p16.htmI imagine if you search CSIS's site, you could find a first-hand assessment from them.