Far too simple and cliche. The U.S. invasion of Afghanistan was anything but conventional and was extremely successful. Other than the initial highly successful invasion of Iraq, the WOT has been all unconventional/counter-insurgency warfare. Your IRA references are also a little silly since the U.S. had a much larger "lesson" in counter-insurgency during the Vietnam war. There really isn't that much parallel between the Police action in Ireland and the full scale counter-insurgencies in Iraq/Afghanistan. The British were no more successful (and in fact were arguably less successful) in Iraq than the U.S.
Originally Posted by Jango
There's no question that there were some large fundamental flaws in the initial stages of the Iraq war. Winning a counter-insurgency really comes down to a solid integrated plan that takes action at the lowest levels of government (Police, infrastructure, governance etc.). U.S. political leaders and high ranking Generals didn't get this lesson until it was flashed in their face by low level Marine/Army commanders operating in Al Anbar in 2006. From 2007 to the end of the war they implemented a very successful strategy that led to them defeating the insurgency. The fatal flaw was that it took them several years to figure this out.
Afghanistan is a very different and difficult situation. The country's incredibly diverse and divisive population makes it extremely difficult to integrate the government across the country at all levels. The place has been a lawless tribal battleground for centuries, it will take more than the U.S. military to change that.
I have no joy in strife,
Peace is my great desire;
Yet God forbid I lose my life
Through fear to face the fire. -Henry Van Dyke