According to an article in the New Yorker magazine by Seymour Hersh, the possibility of using airpower as a substitute for American troops on the ground has caused unease in the military, with air force commanders objecting to the possibility that Iraqis will eventually be responsible for target selection.

"Will the Iraqis call in air strikes in order to snuff rivals, or other warlords, or to snuff members of your own sect and blame it on someone else?" a senior military planner told the magazine. "Will some Iraqis be targeting on behalf of al-Qaida, or the insurgency, or the Iranians?"

With the White House under increasing pressure over its handling of the war in Iraq, senior administration figures are for the first time signalling the possibility of significant troop reductions. In a departure from previous statements the secretary of state, Condoleezza Rice, said last week that the training of Iraqi soldiers had advanced so far that the current number of US troops in the country probably would not be needed much longer.

However, there remains scepticism about the ability of Iraqi forces to take over from the 160,000 US troops in the country. Under the plans reported in the New Yorker, air power will be used to try to fill the gap left by troop reductions. But with the insurgency operating mostly within urban environments, and planes relying on laser-guided bombs directed from the ground to try to avoid collateral damage, there are fears that turning the process over the Iraqis could lead to increased civilian casualties.

"The guy with the laser is the targeteer. Not the pilot ... The people on the ground are calling in targets that the pilots can't verify. And we're going to turn this process over to the Iraqis?" a former high-level intelligence official said.