In the last few months, the revolutions in the Middle East and North Africa seem to have transformed President Obama from a realist into an idealist. What is remarkable about this trajectory is how similar it is to that of his predecessor. When George W. Bush took office in 2001, he disdained Bill Clinton’s idealist “nation building” tendencies and in particular the idea of humanitarian intervention. But after September 11, Bush pursued his own hyper-idealist “freedom agenda”, the centrepiece of which was the Iraq war. When Obama took over in January 2009, he also repudiated the hubris of his predecessor and promised more humility in American foreign policy. During the first two years of his presidency, the United States seemed to have tilted towards realism. But just as Bush reinvented himself after 9/11, so Obama seems to have remade himself since the Arab Spring.

Richard Haass, the president of the Council on Foreign Relations, is quoted in Ryan Lizza’s recent article in the New Yorker – the best account I’ve read of Obama’s foreign-policy evolution – as saying that “the battle between realists and idealists is the fundamental fault line of the American foreign-policy debate”. But as Lizza points out, “no President is always either an idealist or a realist” but rather a mixture of both in varying degrees and at different times in his administration. So although it’s not an either/or question, the idealist/realist distinction is a useful intellectual framework through which to look at US foreign policy choices. What’s also interesting is how the debate between idealists and realists cuts across left-right lines: there are right-wing idealists (e.g. Paul Wolfowitz) and left-wing realists (e.g. John Mearsheimer and Stephen Walt).

Obama started out emphasising realism in reaction to the idealist excesses of the Bush administration. Lizza quotes a speech Obama made in 2006 in which he rejected the neoconservative approach to the Middle East called for “a strategy no longer driven by ideology and politics but one that is based on a realistic assessment of the sobering facts on the ground and our interests in the region”. In his first two years in office, Obama seemed to want to lead an America, that, in the famous words of John Quincy Adams, “does not go in search of monsters to destroy”. For example, after a year in office, Walter Russell Mead urged Obama to be more Wilsonian. (In his book Special Providence, Mead identifies four schools of thought in American foreign policy: Hamiltonian, Jacksonian, Jeffersonian and Wilsonian. Bush’s foreign policy was a mixture of Jacksonianism and Wilsonianism.)

Obama’s initial response to the protests in North Africa at the beginning of this year seemed to confirm his realism. On March 9, as Muammar Gaddafi’s forces threatened Benghazi, I attended an event organised by the Henry Jackson Society in London at which Brendan Simms said the Obama administration – and in particular Hillary Clinton, who had spoken of a foreign policy focused on “defence, development and diplomacy” – had forgotten “the fourth word, which is democracy”. But that now seems like a long time ago. Just eight days afterwards, the United Nations Security Council voted, with US support, in favour of a no-fly zone over Libya. In the two months since then, America seems to have, as New York Times editor Bill Keller put it, rediscovered its “missionary impulse”. This is less Adams than FDR – America as the “arsenal of democracy”. Nor is it just in the Middle East that the administration has become more idealist: Hillary Clinton also seems to have become more critical of China recently.

It’s striking how similar all of this is to what happened to President Bush. Bush ran in 2000 as a realist who would move away from the liberal interventionism of the Clinton era and instead base US foreign policy on interests rather than values (see in particular Condoleezza Rice’s essay in Foreign Affairs in 2000, which focused on China and Russia rather than the Middle East). As Jacob Heilbrunn puts it in a piece in The National Interest about Samantha Power (who a lot of people see as the key figure in Obama’s evolution from realist to idealist), “Obama entered office, like George W. Bush, promising to repudiate the arrogance of his predecessor, only to be seduced by the lure of militant democracy”. In fact, as a brilliant blog post on the New York Times site at the end of March illustrated, there were strong echoes of Bush in Obama’s rhetoric on Libya. In particular, he made strikingly similar arguments for why it is right to use American power to promote democracy.

What do these parallels between Bush and Obama tell us? Lizza observes in his article that “the US keeps getting stuck in the Middle East” and quotes Harold Macmillan’s famous remark about the importance of “events, dear boy, events” in politics. But that seems almost to suggest that the US was twice dragged into pursuing an idealist foreign policy against its will. However, both Bush and Obama made a choice when they responded to events in the Middle East in the way they did. As Germany’s abstention on United Nations Security Council 1973 shows, there were other more possible responses – in particular more realist ones – that other countries with different foreign-policy traditions chose. It seems to me that what forces US presidents to change course from realism is not so much events as America itself and in particular its deeply-rooted idealism.