Obama's "national interest" argument is that another 9/11 will occur if we do not defeat the Taliban in Afghanistan.

"You have to unpack the argument and judge whether our national interest is really at stake. Afghanistan is a mountainous country with a weak central government. We don't have a good record in occupying and running countries we don't understand. Social engineering is dubious. Occupying countries helps the Taliban narrative and Taliban recruiting. The Taliban is heterogenous; many do not share the Jihad desire to overthrow the West.."

to hear Prof. Stephen Walt on Democracy Now, visit
www.democracynow.org/2009/8/25/the_safe_haven_myth_harvard_prof