Level 5

Total Experience Required 4,641 [confirmed]

Level 100 progress: 0.07%

This is roughly:
Killing 16 people in Warzone, or...
Killing 16 people in Execution, or...
Killing 14 people in Wingman, or...
Scoring 3,315 points in Guardian, or...
Scoring 10,090 points in Annex, or...
Scoring 6,107 points in Submission.

Horde (TU4)

Completing 24 waves on Casual, or...
Completing 16 waves on Normal, or...
Completing 12 waves on Hardcore, or...
Completing 10 waves on Insane.

Or a combination of the above. Have fun!