The problem is he can't pull out troops just yet as the government has been completely destabilized. Civil wars and complete chaos would ensue, and Iran would more than likely step in to fix things up, which is not something the States wants. The only way they could pull out is to make it so that Iraq could stand on its own two feet once again, is democratic, and has a leader who has no problem being a puppet of the USA. That's why the reporter was beaten so viciously, so that the new Iraqi government could please their American masters.