My understanding is that the Americans were operating in the south, and I think there are about 3,000 or 4,000--I'm not quite sure. Most of the U.S. troops in the south have been withdrawn, either out of the country entirely or they have been sent to eastern Afghanistan. The American troops that are operating in the south are, as far as I know, operating under ISAF. The Operation Enduring Freedom part of the mission, which is the U.S. controlled part--and they have about 20,000 troops in there under Operation Enduring Freedom--is in other areas of the country.
If you're asking me how the two operations relate, I think the answer is that the ISAF mission is obviously under NATO command and control. The commander of the ISAF commission is a British general. They would be answering to the North Atlantic Council and to the North Atlantic Military Committee and ultimately to the NATO commander. In a sense, there would be international input because NATO members would have more political say over the ultimate objectives of ISAF and the methods by which ISAF carries out its mission, whereas the Operation Enduring Freedom mission is one that is solely responsible, as far as I am aware, to U.S. central command.