'Lt Col Garver told the BBC News website that the strategy could only now start to work as had been planned.

"All the forces initially identified as part of the surge have completed their strategic movements into theatre in Iraq," he said.

"Now everyone is here, this is when General Petraeus intends the surge to start as it was envisaged, with everyone working together to bring the levels of violence down in Baghdad."

He warned it would take 30 to 60 days for the final brigade, which arrived this week, to become fully operational...' US Iraq troop surge 'starts now'

So when did or will 'the Surge' actually start? And when should its efficacy be judged?