Pakistan and Russia have exposed how the United States and NATO do not control the strategic lines of supply into Afghanistan. Anytime a force depends on the cooperation of parties not under its control to sustain it, it is in danger.
The U.S. withdrawal from Iraq gives Iran an opportunity to extend its sphere of influence from Afghanistan to the Mediterranean. This has made bringing about the collapse of Tehran's allies in Syria a central part of a regional containment strategy against Iran. (With STRATFOR map)