The most important facet of a successful military operation is getting supplies to those in combat, and this increasingly is becoming a major issue for US and coalition forces in Afghanistan. Pakistan temporarily closed a major route which funnels supplies to forces in Afghanistan due to militant attacks. Closing the Khyber Pass will make difficult carrying out operations near the border of Pakistan or in eastern areas of Afghanistan. Militants have been constantly destroying vehicles and killing Pakistan soldiers.
The Obama administration intends to send an additional 30,000 troops to the Afghan fight, but if supply lines become cut, it will require diverting thousands of combat personnel to the task of maintaining supply lines. Of course, if Obama can re-establish relations with Russia, it would provide a safer route for supplies.