Complex sentence: The Centre was set up after the reccomendation came from the joint Congressional commission which investigated the terrorist attacks on September 11 2001, this was because their conclusion was that there was information to indicate a terrorist attck was imminent however the information was not analysed in time.
Split into simpler sentences: The centre was set up after reccomendations from the joint congressional commission which investigated the terrorist attacks on September 11 2001. The commission conclused that there was information to indicate a terrorist attack was imminent however the information was not analysed in time.