Why do Liberals say that Bush lied about Iraq and WMD?

This has been a pet peeve for me for a long time. Anyone with a brain knows that Iraq had WMD's, we just never learned what they did with them. I suspect they are either buried somewhere or were moved to another place like syria. Still it irks me to no end when the libs say a lie over and over. In fact, I hate it when anybody tells a lie and that includes conservatives too.