Williams repeatedly told the false story, but now says he misremembered the events. The admission came after crew members that were aboard the helicopter hit by rocket-propelled grenades said Williams was nowhere near the aircraft during the incident.
The evolution of his tale is quite damning. CNN has a timeline of how Williams changed the story over time to put himself in the center of the action.
What’s unclear is whether he purposefully lied (the overwhelming sentiment on Twitter is that he did) or whether he had a false memory of the event. Scoff at the latter if you wish, but there are scientific studies on how unreliable human memory is, particularly during dramatic events.
Even if the more charitable option (false memory) is correct, it suggests that Williams is an unreliable witness to major news events—which is, by itself, enough to seriously damage his credibility.