Cordesman's advice on conducting "non-wars against non-terrorists" boils down to this: lower your expectations and be patient. In many countries, that way of thinking is of necessity the default. In the US, it isn't. Americans want victory, and they want it now. And if they can't win, they ask, why get involved at all? President Barack Obama said in 2011 Iraq was "sovereign, stable and self-reliant". Credit:Reuters In the foreseeable future, there'll be no victory against jihadism. That's partly because it doesn't pose enough of a threat to justify total war against it. Yet the idea that jihadism poses no threat to the US and can simply be ignored is absurd. The danger can't be crushed; it can only be managed. This means confronting it intelligently and patiently - with allies wherever possible, and always measuring the (uncertain) benefits of action against the (uncertain) costs. George W. Bush's "Mission accomplished" declaration illustrates what Cordesman calls the end-state fallacy - the idea that deep-seated conflicts can be brought neatly to an end. So does President Barack Obama's remark on the US withdrawal from Iraq in 2011: "We're leaving behind a sovereign, stable and self-reliant Iraq." Another fallacy is to organise policy around the idea that every conflict has a good side and a bad side. Foreign policy isn't a morality play. Nouri al-Maliki in Iraq and Hamid Karzai in Afghanistan exemplify this second error. Perhaps, at the time, both men were better than the alternatives. Even if they were, they were bound to remain part of the problem.

These points underscore the difficulties, but they don't argue for standing aside. As long as US intervention can influence outcomes, serving US and wider interests at moderate cost, it makes sense. President Bush flashes a "thumbs-up" after declaring the end of major combat in Iraq in 2003. Credit:AP The US and the world will be safer if the Islamic State of Iraq and the Levant - a group that faults al-Qaeda for its moderation - doesn't establish a proto-state straddling the Iraq-Syria border. In my view, that justifies airstrikes against its forces, allied with political demands on Maliki and his government. Part of the calculation is that the costs and risks of airstrikes are limited and commensurate to what can plausibly be achieved. All-out war against this emerging new force doesn't meet that test. Whatever he decides in this case, Obama is certainly inclined to this approach, preferring cold analysis to choosing sides in a war between freedom and people who hate freedom. Witness his statement on Friday, when he said he was looking at options for action against ISIL. Yet it's striking how often he declares wins, however implausibly, and how trapped he sometimes gets in his own simplistic narratives. When the administration rejected Maliki's request for airstrikes earlier this year, you can bet a main reason was: "How do we square this with the claim that we just brought the Iraq war to an end?" It's a claim that should not have been made in the first place. Why was it made? Because of politics, obviously. The pressure to declare victory when nobody has won, to divide factions into fast friends and evil enemies, to ground complex decisions in simple, overriding principles rather than complex trade-offs, isn't self-inflicted. It's imposed by voters. It's all very well to say that leaders need to educate their citizens in the difficulties of foreign policy - which is true - but quite another to do it.

In the US, this civic task gets harder all the time. The political climate is ever less forgiving. According to his critics, George W. Bush wasn't just wrong about Iraq; he lied and betrayed his country. Obama doesn't just disappoint his critics; he disgusts them. Responding to these sentiments and amplifying them at the same time, politicians increasingly find it necessary not just to disagree with each other, but also to repudiate everything their opponents stand for. In this way, US political polarisation tends also to confound security calculations. Cautious realism and strategic patience - the virtues stressed by Cordesman in meeting the new security demands - are hard to practise under the best of conditions. The first requires a space for doubt and good-faith disagreement, which are increasingly frowned upon. The second requires a policy sustained from one administration to the next, not wholesale rejection of what went before. Loading It's an open question whether US politics is capable of delivering the foreign policy the country now needs. Bloomberg