Within the next five years there will be a proliferation of commercial Low Earth Orbit (LEO) satellite systems providing voice/data services to anywhere in the world. Instead of investing heavily in new satellite systems, the military services can use these forthcoming commercial satellite shyster to enhance their existing satellite-based systems. An in-depth study and detailed summary is provided in this thesis for each of the following four commercial LEO satellite systems: Iridium, Teledesic, Odyssey, and Globalstar. Then, a comparison of these systems is performed from the military point of view by using criteria such as antijam protection, security, mobility, flexibility, interoperability, coverage, and capacity. It is shown that an architecture consisting of Globalstar and Odyssey has the potential to provide communications support for DoD's less critical needs which include administration, logistics, and other support functions. Finally , other military applications of these systems are given.