The Roman Empire fell primarily because she was spread far too thin. In our day, Iraq military deployments mean that we can’t scrounge up enough forces to fully occupy Afghanistan at the same time:
The U.S. military has too many troops tied down in Iraq to send needed reinforcements to Afghanistan this year, the chairman of the Joint Chiefs said Wednesday.
“There are force requirements there [in Afghanistan] that we can’t currently meet,” Adm. Mike Mullen said. “Having forces in Iraq at the level they’re at doesn’t allow us to fill the need that we have in Afghanistan.”
Poor Afghanis… I bet they’ll miss us.