The Pashtun tribesmen have several nicknames for the drones that endlessly circle over their mud-walled mountain villages. Some call them "wasps" or "mosquitoes", after the low buzz emitted by the pilotless aircraft's small engines.

But the most telling name is "bangana" – the Pashto word for a thunderclap – after the terrifying impact of a laser-guided Hellfire missile as it slams into a building, often obliterating everyone inside.

Since the CIA launched its first drone strike in Pakistan in June 2004, killing a young Taliban leader, such missile attacks have become an everyday event in North and South Waziristan, along the troubled Afghan border.

Predator and larger Reaper drones have killed up to 1,800 people, according to media estimates gathered by the New American Foundation, including at least two dozen senior al-Qaida operatives and hundreds of more junior militants.

But the drones also kill many civilians – the exact toll is hotly contested – and debate rages, in Pakistan and abroad, about whether they ultimately quell militancy or encourage it.

Washington has few doubts. So far Barack Obama has signed off on over 125 strikes – twice the number authorised by George Bush during the last five years of his presidency. Manufacturers are scrambling to keep up with demand from the CIA.

In the latest attack yesterday, a missile hit a vehicle near Mir Ali, a notorious militant hub in North Waziristan. The identity of those killed was not known.

Pakistanis are distinctly less enthusiastic about the strikes. One US-funded survey of 1,000 tribal residents last summer found that more than three-quarters of people oppose the drone strikes. Only 16% think the strikes accurately target militants while 48% think they mostly kill civilians.

There is evidence the drones exact a heavy psychological strain. Pharmacists report high sales of sedatives and anti-depressants among tribesmen.

Equally serious is the impact on broader Pakistani opinion. Public fury about the drone strikes stoke anti-Americanism in a country where, according to one survey last summer, 60% of people see the US as an enemy.

Oddly, though, media criticism of the strikes has abated in recent months, perhaps reflecting closer cooperation between US and Pakistani intelligence, which, as one analyst said, can "turn the tap" of public opinion.

Drone attacks in Pakistan's tribal belt are controlled by the CIA – the US military runs a separate programme, although the two sometimes cooperate. The unmanned aircraft lift off from a remote desert airstrip in western Balochistan province but are operated by operators sitting behind video terminals at CIA headquarters in Langley, Virginia.

Targets are identified using electronic surveillance and human informers operating inside the tribal belt. Bob Woodward's recent book alleges that the CIA pays 3,000 Afghans to help hunt militants in Pakistan.

Intelligence officials say many of those paid by the CIA work as target "spotters" in Waziristan; those caught by militants are usually beheaded.