The US Government, and by extension the US Military, is exempt from the prohibitions on jammers, which isn't the same as having a licensing system. The law simply doesn't apply to them.
"The provisions of this section shall not be applicable to...devices or home electronic equipment and systems for use by the Government of the United States or any agency thereof."
"Devices and home electronic equipment and systems for use by the Government of the United States or any agency thereof shall be developed, procured, or otherwise acquired, including offshore procurement, under United States Government criteria, standards, or specifications designed to achieve the objectives of reducing interference to radio reception and to home electronic equipment and systems, taking into account the unique needs of national defense and security."
The prohibition on jammers is very specific as to exempt uses, and there is no licensing mechanism to allow any other use.