The Afghanistan war was a logistical nightmare. The United States is accustomed to bringing in by sea most of the stuff needed to support a war. This was not possible in Afghanistan. Although we had permission to fly over Pakistan to reach Afghanistan, using Pakistani ports was not a big help. Material unloaded at Pakistani ports would then have to move by train and (mostly) truck into Afghanistan. The large number of anti-American Islamic radical organizations in Pakistan made this kind of movement dangerous. Some stuff has come by sea, or is bought locally in Pakistan and trucked in as commercial goods. This left most of the supply movement for U.S. troops in Afghanistan to the air force transports. This brought about a unique situation in American military history. But mutual agreement among the services (after many decades of debate, plus a lot of practical experience), the army is basically in charge of logistics for the other services when operating on land. Even the marines, once they get about a hundred or so kilometers from the ocean, depend on the army to make the logistical arrangements. The navy, of course, sees to it that the supply ships get to local ports in one piece. The army also has to take care of engineering (building and repairing roads and bases) and distributing supplies on the ground (truck transport, river movement and railroads if available, which they aren't in Afghanistan.)

But in Afghanistan, the army has to depend on the air force to bring everything in. This has caused more than a few tense moments at various headquarters, as priorities are decided. We were lucky that the most effective forces were low maintenance light infantry and bombs flown in on heavy bombers from the island air base of Diego Garcia. We now have bases in Central Asia (north of Afghanistan) that can be supplied by the Russian railroad system, although most of the bombs are still coming from Diego Garcia (via fast sea transport from America.) Expect to see a lot of commotion in Congress over the next year or so about logistics and transportation. The brass have no doubt already pointed out that if we needed to put a lot of ground troops into Afghanistan, we would have been in big trouble. As it is, after five months we have been able to get no more than two weak brigades into Afghanistan, and are depending on the special forces to recruit and train local Afghans to provide back up for the few infantry our meager logistical capabilities have allowed us to put into Afghanistan. 

In addition to the army being responsible for logistics, they are also in charge of defending air bases and any other American installations. This ties up a lot of American troops, although we are getting help from our allies. But the army is coordinating logistics for the allied troops as well. Fortunately, there's not a problems with air defense, for the army is responsible for providing anti-aircraft weapons as well. As a result of all this, the army will be rethinking how to handle it's many responsibilities. This is yet another example of the old axiom; "amateurs study tactics, professionals study logistics."