The 60 Minutes interview with General McChrystal about the situation in Afghanistan (hyperlinked) has been generating much discussion. Besides the general discussion about McChrystal's plan, one line should jump out: the general is described as a "prisoner of geography." Understanding that point is key to better understanding the situation of Afghanistan.
Comparing Afghanistan with the previous American war, the one in Iraq, that is successfully being transferred from Coalition combat activities to Iraqi martial policing after a near defeat:
Population: 28.4 million
Area: 251,827 square miles (652,230 square kilometers) - 48% bigger than Iraq
Physical-Political Zones: Flat, void deserts in the south, middle highland section enclosed via mountains, the north is a collection of mountains, hills, and valleys. Rugged terrain in the east makes the nominal border with Pakistan hard to control. Controlled borders with the former Soviet states to the north. Hostile Iran to the west.
Population: 28.9 million
Area: 169,235 square miles (438,317 square kilometers)
Physical-Political Zones: Population lives primarily in the central-to-eastern core running north and south. Physical geography here is flat, wide, and green. Deserts to the west and south offer pros and cons for securing the border. Hostile Iran to the east. Mountains in north but these are inhabited primarily by friendly Kurds with a few Communist rebels tied down by Turkey.
Another factor to remember is the amount of troops the Coalition has compared to the Soviet Invasion. The Soviet Invasion topped out at around 120,000 soldiers while top commanders said they would need 300,000 to control the countryside. Right now there are 64,500 Coalition troops (not all in combat roles) as of July 2009.