The Andorian Defense Force was a military organization operated by the Andorian people in the 24th century. Andorians wishing to enter the Defense Force trained at the Andorian Academy.
The Defense Force operated starships in local space in defense of Andor and the Federation. One mission undertaken by the Force was track down anti-Federation Andorian renegades. Another task of the Defense Force: they forced ships to avoid the energy field remaining from the 2069 collapse of the Andorian wormhole. (Last Unicorn RPG module: All Our Yesterdays: The Time Travel Sourcebook)
Sirta D'Qua and her father both served in the Defense Force. Following her exemplary service in a battle with Andorian renegades Sirta was invited to enter Starfleet Academy, which she accepted, eventually going on to serve in Starfleet. (TNG video game: Away Team)