One reason the United States often gets called on by its allies during military crises has nothing to do with weapons or combat, but with logistics. The U.S. has been, for nearly a century, the world leader in moving military personnel and cargo to where it is needed and doing so under the most trying conditions (of nature or enemy interference).
Currently the United States spends $1.5 billion a year and uses 180,000 personnel to move military personnel and material. This does not include additional spending for war related logistics (as in places like Iraq and Afghanistan) that increase that spending to close to $8 billion a year. The level of activity, and length of time the U.S. has been at it make access to American logistics resources and specialists something much sought after by American allies. While the allies appreciate having American aircraft or ships move stuff for them, often it’s just the excellent and experienced advice from the Americans that is needed.
This most visible American military logistics organization is called U.S. Transportation Command (USTRANSCOM) or Transcom for short. The air force component is AMC (Air Mobility Command), the navy contribution is MSC (Military Sealift Command) and the army contributes its expertise in handling “the last mile” of using ground and river/canal transport to get material to the end-user.
Since World War II military logistics has evolved from a largely army chore to one that depends much more on air freight. It was during World War II that the United States found it had a talent and capacity for truly massive and unprecedented logistical efforts on a global basis. Most of this was run by the army, which had more ships under its control than the navy. The army ships and coastal craft were mostly for logistics and that fleet of over 110,000 vessels contained very few warships. After World War II the navy got control of the army fleet and the Army Air Force became a separate service and developed a huge fleet of air freighters. The army developed several generations of trucks and innovations like rapidly built temporary pipelines and a global network of transportation contractors.
These days the largest component of Transcom is AMC, which contains 79 percent of the 180,000 Transcom personnel and nearly as much of the budget. Most of the Transcom personnel are reservists or civilians, and a lot of the actual cargo moving is done by aircraft, ships and trucks hired for the occasion.
AMC and the army move more tonnage, but if you want something moved anywhere real fast (very common in wartime), AMC gets it done. AMC does this with a fleet of 1,100 aircraft (40 percent aerial tankers, the rest freighters like the C-17 and C-130). Last year AMC carried out 105,000 sorties, 20 percent of them aerial refueling, the rest moving personnel and freight. MSC moved 502,000 measurement tons (568,000 cubic meters of cargo) as well as 6.6 million tons of fuel. Most of everything moved is via contractors (half the air freight, 64 percent of sea freight and about the same portion of land movement although in the U.S. its 88 percent).
The 27,000 people (98 percent civilian) in the Defense Logistics Agency supervises the movement of all the supplies from manufacturer to consumer and handle the logistics planning and administration while Transcom specializes in moving stuff.