Simplify the following text for a Grade 12 native English-speaking person.
Original: Alongside the internal Security Service ( MI5 ) , the Government Communications Headquarters ( GCHQ ) and the Defense Intelligence Staff ( DIS ) , it operates under the formal direction of the Joint Intelligence Committee ( JIC ) .
Simplified: It works with the Security Service ( MI5 ) , Government Communications Headquarters ( GCHQ ) and the Defense Intelligence Staff ( DIS ) .