Lying is when you say something you believe is false. I suspect that there are a lot of people, including perhaps especially some politicians, who are incapable of believing that anything they say can possibly be false. Therefore such people are, in a sense, incapable of lying.

However trying to get people to believe that there was some connection between the Iraq regime and Al Qaida, in face of plenty of evidence that there was no such connection, would have been a lie for most people.