From Halopedia, the Halo wiki
The Committee to Preserve Gao Independence (CPGI) was a group of protesters formed on the planet Gao. It was founded and supplied by Arlo Casille.
In 2553, the UNSC occupied parts of Gao with permission by the Gao Republic under President Tejo Aponte. The Committee was supposedly attacked by a UNSC UH-144 Falcon without provacation. A spokeswoman appeared on BuzzSat relayed some of this information to the public.