The Fleet Marines is the military ground force arm of StarFleet. They are called upon when more is needed than standard security officers. Marines are responsible for ground and boarding party missions that with a high probability that high levels of force will be needed, possibly for an extended period of time.
With access to a more powerful arsenal of offensive and defensive weaponry, the marines train to assault, take, and hold an area against an entrenched enemy. Marines will also be called upon to repel borders, conduct rescue operations, and enforce Federation Law.