Thoughts From a Talk by LTC John Nagl

Nagl says that the major lesson that the US military establishment drew from the first Gulf War was that the combined AirLand doctrine that utterly destroyed the relatively respected Iraqi forces was an absolute success, but it required more investment to ensure that the US retained its advantage in the field. From the hatch of a tank the view point was different and therefore the lessons that were learned also differed. Nagl left his Gulf War experience convinced that for the foreseeable future no one would bother to challenge the US in conventional warfare. This dominance (and the world's tacit acknowledgment of it) would push future wars either to the top (WMD) or the bottom (guerrilla/insurgency tactics). The book had already been written on WMD, but the American military's counter-insurgency manual had been gathering dust for years. The experience (and more specifically the failures) of the Vietnam War, rather than challenging the military to devise better ways of dealing with low level warfare, led to it neutering the counter-insurgency capabilities it had gained during the war. [This topic is also well covered in the New American Militarism by Andrew Bacevich]
Nagl emphasizes the importance of the military learning by long term institutionalization of changes rather than merely adapting with short term change in tactics and was adament in his belief that "this is the kind of war we will be fighting for the foreseeable future." Besides the importance of making good decisions with regard to doctrine, tools, technology and emphasis, it is even more important to be able to get inside the 'decision loop' of the enemy. It is not enough to design, approve and implement new technology to stop a certain design of IEDs when it only takes a week or two for the insurgents to defeat it with 12 dollar radio shack parts. US forces must be able to innovate and change ahead of the insurgents.
The focus of the new COIN doctrine is to first empower each individual soldier as decision maker, and then make the knowledge that the "best weapons [against an insurgency] don't shoot bullets" at the fore of every soldier's thought process. Killing insurgents is only valuable if it helps in building and maintaining the SWEAT-MS infrastructure (acknowledging the military's excessive love for acronyms, I still like this one; Sewer, Water, Electricity, Academics, Trash, Medical, Security.) Otherwise the dead insurgent's shoes will merely be filled by another disgruntled individual.
On a side note, an audience member brought up Sir Aylmer Haldane's work, "The Insurrection in Mesopotamia" (about the British experience putting down the Iraqi revolt in 1920) and asked if that experience proved that low-force, 'hearts and minds' COIN campaigns were mistaken strategy. I believe that the opposite is true. To paraphrase what other much wiser commentators have said, history doesn't repeat, it merely rhymes. The methods used in that case are not applicable to the Iraq of today. The Roman subjugation method of 'kill, salt and burn' and the Japanese Three All doctrine (Kill all, Burn All, Loot All) cannot be done by the US military in the 21th century. The information revolution has ensured that.In the end, the lesson that should and must be drawn from Iraq, no matter how the situation turns out, is that either conventional war fighting capabilities are not enough, or the mission's the US military should be called upon to perform should be much more limited.