In May of last year, President Obama announced that future US air strikes against suspected al-Qaeda targets in Pakistan and Afghanistan would be authorised only when there was a "near certainty" that civilians wouldn't be harmed.
The new policy was in response to growing hostility to the strikes, especially in Pakistan, where several hundred civilians are believed to have been killed by US military action. It is, after all, quite difficult to persuade people that you're trying to help them confront a terrorist threat if you end up killing them in the process.
So it is totally baffling that the "near certainty" principle apparently doesn't apply in Syria or Iraq, where US air strikes are now targetting Islamic State fighters. According to the American investigative reporter Michael Isikoff, reporting for Yahoo News, "a White House statement ... confirming the looser policy came in response to questions about reports that as many as a dozen civilians, including women and young children, were killed when a Tomahawk missile struck the village of Kafr Daryan in Syria's Idlib province on the morning of Sept. 23."
So how does the White House justify its casual acceptance that civilians in Syria and Iraq are likely to be killed by US missiles? Ah, the "near certainty" principle applies only "outside areas of active hostilities", says a spokeswoman for the National Security Council. And that's not the situation in Syria or Iraq, obviously.
So that's all right, then. Which, of course, it isn't. I can think of no policy more likely to achieve the precise opposite of what's intended than one which blithely accepts that innocent civilians will be killed. As a recruitment tool for IS (also known as ISIS or ISIL), it's hard to think of a more effective weapon.
I seem to recall that the Obama administration was "appalled" by civilian casualties during the most recent Israeli military action in Gaza - "totally unacceptable and totally indefensible" was how it described an Israeli strike on a UN school being used as a shelter for civilians. I don't say it was wrong to speak out then; I do say it is wrong now to lower the bar for authorising air strikes against IS.
But let's be absolutely clear: IS do need to be confronted and defeated. The argument is not about the goal, but about the means. A horrific UN report published yesterday accused the group of carrying out mass executions, abducting women and girls as sex slaves, and using child soldiers in what it said may amount to systematic war crimes.
According to the UN High Commissioner for Human Rights, Zeid Ra'ad al Hussein: "The array of violations and abuses perpetrated by ISIL and associated armed groups is staggering, and many of their acts may amount to war crimes or crimes against humanity."
So instead of air strikes aimed at solitary military vehicles trundling through the desert, or apartment blocks where IS leaders may or may not be sheltering, perhaps there's another way. A way that would mean turning our attention back to Syria, which is where IS is based, where it is strongest, and where it has greatest freedom of action.
In a fascinating recent article for the New York Review of Books, two former senior US National Security Council officials, Steven Simon and Jonathan Stevenson, sketched out a very different approach, starting from the premise that the best way to defeat IS is to change the balance of forces on the ground in Syria.
"The Syrian state has already effectively collapsed," they wrote. "The country has split into pieces, is stuck in a civil war now in its fourth year, and is experiencing one of the largest humanitarian crises since World War II, with almost 200,000 dead, over three million refugees, and 6.5 million internally displaced people. Continued intense fighting will only amplify the havoc wreaked by ISIS and other jihadist groups."
What they propose is that the UN tries to encourage locally-negotiated truces between government and rebel forces - they say many unofficial truces are already in place, in and around cities like Damascus, Homs and Hama. "The most realistic short-term policy goal in Syria is to find ways to limit the areas of the country in direct conflict, with the aim of both containing extremist violence and significantly reducing the number of non-combatant deaths.
"This goal is not as far-fetched as it sounds, and there is already a basis for pursuing it: through a series of local cease-fires that could, if properly implemented and enforced, provide a path toward stability in several regions of the country, even as conflict continues elsewhere."
It would mean acknowledging an uncomfortable new reality: that the alliance of Western and Arab forces confronting IS are now on the same side as President Assad. It may be only temporary, and it can probably never be openly admitted, but there are some signs that both sides understand that IS pose a greater threat to each of them than they do to each other.
Peace, like democracy, cannot be imposed from above, or from outside. But if the two sides in Syria's civil war can agree to at least a few temporary local truces, they may be better able to turn their attention to IS. That's certainly what would be in their best interests, and in the interests of their foreign backers, whether Iran, Saudi Arabia, Qatar or Turkey.
It is local people who will defeat IS, both in Syria and in Iraq. Yes, foreign powers can help, by training them and arming them. But not by bombing them and their families.