Gen David Petraeus, the new US commander in Afghanistan, is to review the controversial doctrine of “courageous restraint”, according to Pentagon sources.

He is to re-examine the rules which some soldiers believe have prevented them from defending themselves.

“There will be no change in overall policy but all aspects of tactics and implementation will be looked at afresh,” a Pentagon official told The Daily Telegraph. “The issue of ‘courageous restraint’ is a controversial one on the ground and there may be ways it can be modified.”