EVERY incoming president is required to send Congress a National Security Strategy. Some of these documents are abstract and forgettable but others really do provide a clue to the future. One such was the document George W. Bush signed in 2002, which gave warning that America would act against foes seeking dangerous military technologies before such threats were fully formed. A year later the Bush administration cited precisely this doctrine to justify the invasion of Iraq and the toppling of Saddam Hussein.

Barack Obama’s National Security Strategy, published on May 27th, has a different emphasis. Mr Obama opposed the invasion of Iraq. His document does not endorse Mr Bush’s doctrine of pre-emption. Nor, though, as the Iranians will doubtless note, is pre-emption explicitly disavowed. As a last resort, says the strategy, “the United States must reserve the right to act unilaterally,” albeit adhering to “standards that govern the use of force”.

A bigger difference between the approaches of the two presidents is in their estimate of American power. Whereas the Bush document started by stressing America’s “unprecedented and unequalled” strength and influence, Mr Obama’s acknowledges the limits to America’s power. “No one nation—no matter how powerful—can meet global challenges alone,” it says.

Reflecting this new sense of limits, the Obama doctrine is not only less ambitious than his predecessor’s but arguably less idealistic. Mr Bush said his aim was “to promote a balance of power that promotes freedom”. Under Mr Obama the neocon notion of spreading democracy by force has gone. The Obama approach recognises the need to advocate universal values, and the importance of living by them at home, but says that America “will not impose any system of government on another country.” America, the new document says, will seek “principled engagement” with non-democratic regimes.

Mr Obama also seems eager to narrow the circle of America's enemies. The focus now is not on “terrorism” broadly, or on Islamic extremism, but more precisely on “defeating al-Qaeda and its affiliates in Afghanistan, Pakistan, and around the globe”. The new document places an unusual emphasis on rebuilding the economy as one of the nation’s top national-security priorities, and it is the first National Security Strategy to warn against the security threat posed by “individuals radicalised at home”.

And yet the new document on its own hardly amounts to a full “Obama doctrine”. At most, a document concocted for open publication and congressional consumption by officials in the White House offers a set of clues to how a president will act on national security. It is not a blueprint. To figure out what Mr Obama is about, it is necessary to watch what he does as well as what he says. A gap has already opened between the two: the prison camp at Guantanamo has not yet been closed, for example. If a single theme emerges, it is that the new president believes that America has overreached abroad and must rebuild at home. Not inspiring, perhaps, and certainly not surprising. But many will regard it as refreshingly realistic.

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