Choke point

With reports of the Taliban shutting off the Khyber pass (which has since re-opened) I was wondering what that means in a larger strategic sense.The military has gone on record as saying these attacks were insignificant, but Danger Room has some context that makes you wonder (emphasis added):

Here's the problem: the mission in Afghanistan are sustained by supplies trucked in overland from the Pakistani port city of Karachi. According to the Armed Forces Press Service, the Khyber Pass route provides three quarters of the supplies for U.S. troops in Afghanistan, creating a vulnerable choke point. Late last year, militants stepped up attacks in the Khyber Pass area; they also staged a dramatic attack on a NATO truck depot near the border city of Peshawar, destroying dozens of military trucks. 

The Taliban aren't stupid. They can count.

• Number of ports in Afghanistan: zero. 
• Number of countries bordering on Afghanistan with deep-water ports: two (which is effectively one, since one of those countries is Iran)
  

Driving up from Karachi, we go through Spin Boldak or Khyber. That's two roads for all the shipped in gear. We can fly stuff into the northern border countries, but no way we want to spend that kind of money over the long haul.

It's a helluva place to fight a war.