ONE day in March an American drone circled above Pakistan's North Waziristan tribal area, zeroed in on a gathering of village men, some of whom were armed, and unleashed three missiles in quick succession. It turned out to be a meeting to settle a dispute over a chromite mine. Most of the 40 or so killed were civilians, according to accounts, though a dozen Taliban also died in the attack, including a local commander, Sherabat Khan. The Taliban nowadays often adjudicate quarrels in the tribal areas, a wild buffer zone that runs along Pakistan's border with Afghanistan.

The attack illustrated two problems with the drone war in the tribal regions: the risk of civilian casualties, and Pakistan's ambiguous attitude towards America's use of drones. Pakistan's army chief, Ashfaq Kayani, called the strike a “complete violation of human rights”. For Pakistan, the difficulty went beyond civilian casualties. Khan was a lieutenant of a notable warlord, Gul Bahadur. But Pakistan considers Mr Bahadur to be a “good Taliban”, ie, one who has agreed to fight only in Afghanistan, not on Pakistani soil. After the strike, he threatened to tear up the deal.

Relations between the governments in Islamabad, Pakistan's capital, and Washington, DC, are deeply troubled by the issue of drones. Though it publicly denounces the drone strikes, Pakistan certainly does not want all of them stopped. Indeed, the co-operation of Pakistani intelligence is crucial to employing the drones. But the army wants the number of strikes reduced, concentrating on targets both countries can agree on. America has told Pakistan bluntly it must either flush the Taliban and other jihadists out of their safe havens in North Waziristan, or it will continue with what amounts to an assassination campaign there. Pakistan says it cannot launch a ground offensive in North Waziristan because its armed forces are already stretched.

The drone attacks, a supposedly “secret” programme started by the CIA in 2004, have been ramped up over the past three years, with a record 118 strikes last year and 50 so far in 2011. The drones started under President Pervez Musharraf, the former military ruler. There were just nine strikes from 2004 to the end of 2007. According to Pakistani officials, it was supposed to be a highly selective programme for eliminating terrorist leaders in the tribal areas, under an understanding that gave the Americans the use of at least one remote Pakistani air base for the drones. The drones also take off from Afghanistan, but are operated thousands of miles away by a “pilot” at a desk in America, watching a video feed from the aircraft. A successful hit is known in the CIA as a “bugsplat”. It is all horribly like a video game.

The New America Foundation, a Washington think-tank, found that up to 2,551 people have been killed in the strikes since 2004. Based on press reports, it estimates that 80% of them were militants, rising to a pretty astonishing 95% in 2010. In recent months, there has been a move away from blowing up compounds to targeting vehicles, where militants can more easily be hit without killing civilians. Even for compounds, smaller missiles are used to try to limit the damage to the separate male living quarters. Perceptions on the ground, however, are often different. The foundation's own poll in the tribal areas last year found only 16% believe the drones accurately target militants. But many locals privately support the strikes against extremists who have overrun their homeland.

Accepting the figure for the success rate in killing militants nevertheless means that fully 500 or so Pakistani civilians have been killed since 2004. Unlike, say, in the war in Afghanistan, there is no investigation of civilian casualties, and no compensation paid. Transparency and accountability are absent, and some question the legal basis of the attacks. The programme is a charade because the CIA never admits to it and Pakistan pretends that it does not co-operate. A legal action launched this month, initially in Pakistan, with the backing of Reprieve, a campaigning group, seeks the arrest of a former CIA lawyer, John Rizzo, who boasted in a magazine interview this year that he used to approve a monthly list of some 30 individuals to be targeted by the drones.

Whatever the outcome of that case, a debate will grind on about whether the strikes are harming al-Qaeda and related groups, or spurring on Afghanistan's powerful insurgency. According to the New America Foundation, out of the 2,600-odd deaths, 35 were recognised militant chiefs, or just 1.3% of the total. Among the successes was the fearsome leader of the Pakistani Taliban, Baitullah Mehsud, who was the country's number one public enemy. Still, the vast majority of targets have been low-level fighters. All the while, the number of suicide attacks in Afghanistan, many launched from Pakistan, has soared over the past year or more.