Mars Defense Perimeter

The Mars Defense Perimeter was a Starfleet defensive program set up to defend the inner Sol system -- specifically, pleanet Earth -- from attack from outside the system.

During the Borg Incursion of 2366-2367, a number of ships comprising the Mars Defense Perimeter were easily destroyed by an approaching Borg cube. 

In 2371, the USS O'Keefe was assigned duty on the Mars Defense Perimeter.