The issue of whether or not intelligence was manipulated depends of what you mean by manipulate. Numerous intelligence agencies provided what we now know was faulty intelligence about WMD in Iraq. There were other intelligence agencies that cast doubt on Saddam Hussein having WMD. Colin Powell has now said that much of the intelligence that was given to him for his February 5, 2003 speech to the UN was inaccurate. Bush ignored ANY intelligence warnings that said Saddam Hussein did not have WMD and pressed the Congress for permission to attacking Iraq. It is clear, that the intelligence that indicated Saddam did not have the weapons programs was not provided to Congress before they voted for war or to the American people.
In addition there were people such as Professor Record at the Army War College that said a rogue state such as Iraq would never attacked the United States even if they had WMD because to do so would bring an end to their dictatorship. Professor Record clearly showed that there was never a case where a rogue dictatorship attack a major power. In addition, for a dictator to supply WMD to terrorists for use against a major power would result in the end of the dictator if that WMD were traced back to him.
Bush used the intelligence that supported his decision to attack Iraq and he and ignored any intelligence that did not support his preconceived notion of removing Saddam from power. If Congress had ALL the intelligence before they voted, it is very likely Bush would never have received the permission from Congress to invade Iraq. We need to learn the extent of the intelligence that Bush ignored that indicated Saddam did not have the WMD.