This is the problem when you depend solely on intelligence provided by dissidents, since we did not have anyone in the country at the time providing intelligence directly to us.
There were weapons inspectors on the ground in Iraq which Bush pulled out prior to launching the invasion. The whole idea that "we didn't have the intelligence because we didn't have anybody in the country" is such BS.
I'm talking about imbedded intelligence, such as CIA, not weapons inspectors. Remember, our inspectors were being shuffled around and denied access to many areas prior to the second phase of the war, so that alone provided belief behind the "he must be hiding them" claim which most of the Western nations governments believed.