Mars Defense Perimeter

The Mars Defense Perimeter was a planetary defense system in the Sol system designed to protect the inner planets, including Earth from attack. The perimeter was made up of attack ships and Mars Defense Perimeter platforms.

In 2367, a Borg cube was easily able to penetrate the perimeter, destroying several ships that attempted to intercept it. 

A second Borgattack in 2373 was again able to penetrate the perimeter. 

During the Breen Attack on Earth in 2375, the Breen were able to demolish the Mars Defense Perimeter and the Starfleet Third Fleet in two hours.