"It's emerging that although perhaps the overall strategy is not being changed, it's certainly being fine tuned," Bays said. "I think behind the scenes General Petraeus ... is looking at every detail of this operation."

McChrystal resigned in June after Rolling Stone magazine published a profile of the general that quoted his staff disparaging high-level officials in the US administration.

Barack Obama, the US president, replaced McChrystal with Petraeus, who oversaw the production of the US army's manual on counterinsurgency and was the commander of US troops in Iraq during President George Bush's troop "surge".

'Fighting corruption'

Some of the language in the new rules use more direct language than that of McChrystal's.

Afghan directive
Main points of Petraeus' new rules in Afghanistan:
   
  Secure and serve the population
  Live among the people
  Confront a culture of impunity
   
 Read the document (pdf)
 

Whereas McChrystal urged Nato forces to "confront self-serving officials" and not "look the other way," Petraeus instructs troops to "confront, isolate, pressure and defund malign actors" and to refer them for prosecution "where appropriate".

If Nato does not act against officials who don't work "for the people," the document says, "we will appear to be part of the problem".

Petraeus does not mention the Taliban by name, but addresses the need to reintegrate "reconcilables" whose grievances can be addressed while working to "kill, capture, drive out or 'turn' the irreconcilables".

In his guidance, McChrystal never made any mention of reintegration - an objective increasingly emphasised by Hamid Karzai, the president of Afghanistan.

Petraeus' also tells Nato forces to act as if "money is ammunition" by being wary of who receives funding, such as the widely used Commander's Emergency Response Programme, which enables low- and mid-ranking military officers to fund projects ranging from a few to several hundred thousand dollars.

"Pay close attention to the impact of our spending and understand who benefits from it," the document says. "How we spend is often more important that how much we spend."

Word for word

In many respects, however, there is little difference between the two documents.

Both echo the core philosophy of counterinsurgency - that securing the population is more important than winning military victories against the Taliban.

McChrystal referred to taking "control of the population" from the enemy, while Petraeus instructs troops to "secure and serve" the Afghan people.

Both documents, in nearly identical words, say that Nato forces need to live, eat, train, plan and operate with Afghan soldiers and policemen.

They also address the way troops should conduct themselves among the people on a day-to-day basis; how they should drive, dress and act.