The Navy has most of the top line commandos (about 700 SEALs, versus some 300 Army Delta Force) as well as a number of support units (with various types of small boats for getting SEALs ashore from submarines or surface ships.) To maintain control over all of this, the Navy has six NSWU (Naval Special Warfare Units) overseas (in Guam, Bahrain, Germany, Puerto Rico, Panama and Spain) to provide training and housing facilities for six or so SEAL platoons that may be operating in that area. SEALs can also be moved by air, which is how they got to Afghanistan.
Where the Operators Are- While you don't hear much about American commandos in the news, many actually spend about half their time outside the country, either training with foreign armed forces, scouting potential operations or actually doing something that is not likely to get reported. The U.S. has some 8,000 commando type troops. The 2,000 Rangers operate in large units for raids and reconnaissance and spend most of their time in the United States. Most of the Rangers are young, non-career, troops and spend most of their time training at their U.S. bases. The 5,000 Special Forces are career soldiers who spend a lot of their time studying foreign languages, cultures and politics. In addition, they study military specialties (weapons, explosives, engineering, medicine) and what we would consider commando operations. Special Forces troops spend about half their time overseas, either on training missions to assist foreign armies, or on reconnaissance operations. Some of the snooping jobs are done in cooperation with the CIA. It's important to remember that Special Forces are a unique form of commando, who rely more on negotiating than fighting, but can shoot it out with the best of them if need be.