Joint chiefs chairman says duration of US military presence in Iraq is ``unknowable'': Joint Chiefs of Staff Chair Gen. Richard Myers "said that if he and the top U.S. commanders in Iraq were to 'sit around a table, I think we could draw out a pretty good diagram of where we think we're going to go' with winding up the Iraq operation.

"On the other hand,... 'Actually, the things we've sat around and talked about before have been wrong on every count,' he said with a chuckle."