Warburg is a free-for-all zone, it's so chaotic even the heroes will fight each other. It's actually a rebel island led by Marshall Blitz, who was apparently frustrated that Lord Recluse was sitting on all those missiles and not shooting them at Paragon City. In the chaos, everyone is now trying to locate launch codes to the missiles to use for their own purposes. Once launched, Warburg warheads can stay in orbit indefinitely until needed.
In addition to the missiles, Warburg is also the site of the failed Arachnoid super-soldier project. Spider-like monsters who were set free during the initial rebellion, these creatures infest the tunnels under the island. Coincidentally, this is the area where launch codes can be found.
Oddly enough, the Arachnos troops sent to put down the rebellion are severely outgunned, as if Recluse was intentionally sending weaker units in. The reasons for this are unknown, but in the meanwhile it's best to take advantage while you can.