The Big Question: What is neo-conservatism, and how influential is it today?

Why are we asking this question now?

David Cameron yesterday delivered a major foreign policy speech warning against the spread of anti-Americanism, yet distancing himself from the neo-conservatives who have dominated US foreign policy under President Bush. Mr Cameron describes himself as a "liberal conservative" rather than a neo-conservative.

But what is neo-conservatism?

The ideology is difficult to define. It used to be a blend of liberal democracy and hawkish foreign policy. Today the term refers to idealistic hawkishness. The philosophy has been around since the middle of the 20th century, if not earlier. Some trace its origins to the liberals and social progressives who strongly backed the Second World War. One of its founders was the US intellectual and writer Irving Kristol, a former Trotskyist who later described himself as "a liberal mugged by reality". In the 1950s and 1960s the neo-conservatives adopted a similarly robust view towards the Soviet Union, breaking first with the anti-capitalist New Left, then with the Washington foreign policy establishment that came to support Cold War détente with Moscow.

How did it become identified with the Republicans?

For a long period it wasn't. Harry Truman and John Kennedy in some respects could have been labelled neo-conservatives. What changed things was the more dovish national security stance of the Democrats, after George McGovern won the party's presidential nomination in 1972. Thereafter Democratic Senator Henry "Scoop" Jackson of Washington, an anti-Soviet hawk, became a focus for the movement. Among his staffers were Paul Wolfowitz and Richard Perle, intensely pro-Israeli and later two of the most influential neo-cons under Ronald Reagan and George W Bush. They opposed not only the McGovernite Democrats, but also the "pragmatist" détente policy of Nixon, Kissinger and Ford.

What happened after that?

The neo-conservatives first really came into their own under Ronald Reagan, who decided to challenge the Soviet "evil empire" head on. But they gradually parted ways with Reagan as he shifted towards détente with the reformist Soviet leader Mikhail Gorbachev. More idealistic neo-conservatives were also dismayed by President Reagan's backing for anti-democratic regimes simply because they were US allies and anti-Soviet. Reagan's support for Israel also fell short of neo-con expectations.

Why did the neo-cons triumph?

Ideologically, because of the collapse of Communism and the Soviet Union. This was seen as vindication for the neo-conservatives - even though the great moment came when the supremely pragmatic George Bush senior was President. They remained in opposition under Bill Clinton, but in the 1990s quietly came to dominate Republican foreign policy. Their manifesto was A Project for the New American Century, their mouthpiece the Weekly Standard magazine, edited by Bill Kristol (son of Irving). Among the signatories of PNAC were Dick Cheney and Donald Rumsfeld the present Defence Secretary, as well as Wolfowitz and Lewis Libby, chief of staff for Cheney when the latter became Vice-President. PNAC called for higher defence spending, the promotion of democracy and freedom around the world, and the creation of a world order "friendly to our security, prosperity and values". George W Bush's victory in 2000 gave them power; 9/11 and the "war on terror" gave them their cause.

What effects has it had?

Enormous, and most would say, disastrous effects. The ousting of Saddam Hussein had been on the mind of Paul Wolfowitz, for one, since the early 1990s when he was a senior Pentagon official under the first President Bush. The decision to allow Saddam to stay in power after the 1991 Gulf War was a mistake, he believed. The "war on terror" gave Wolfowitz - now deputy Defence Secretary - and his fellow believers their chance. Neo-cons at the Pentagon and the Vice-President's office twisted the intelligence to prove that Saddam had WMDs and imply he had a hand in 9/11. For neo-cons, Iraq was to be a test run for the reform of the entire Middle East and the spread of democracy in the region.

By any yardstick, the policy has been a failure. Iraq is in chaos, and the Middle East has become less rather than more stable. Around the world, anti-Americanism has increased hugely. Neo-conservatives in their turn have been "mugged by reality" - the reality being that even the sole superpower America is not omnipotent, and that ancient civilisations are not to be transformed by elections alone. Above all, they stand guilty of naivete.

How does George Bush fit in?

After September 11, the administration's security policy was powered by the alliance of Cheney and Rumsfeld (both, incidentally, hardline "realists" rather than conservatives with an ideological mission), who dominated an inexperienced President. But the balance shifted as Iraq went wrong. Bush realised the US could not go it alone. Condoleezza Rice, a more moderate figure, gained influence, as the stars of both Cheney and Rumsfeld waned. Wolfowitz left to become chairman of the World Bank, while Libby resigned after his indictment in the CIA leak affair.

Have the neo-cons been discredited?

Not necessarily. Their credibility has been shredded by Iraq, but Kristol and others blame the failure not on the original grand design, but on the poor organisation of the occupation by Rumsfeld and his minions at the Pentagon. The original principles of PNAC are still very much the cornerstone of US foreign policy.

The crucial test case of neo-con influence is now Iran. In contrast with Iraq, Bush's instinct seems to be to let diplomacy run its course in the dispute over Tehran's suspected nuclear weapons programme. But neo-cons are urging him (and/or Israel) to take no chances and bomb Iran, just as Iraq was attacked three years ago.

Do the neo-cons have a British equivalent?

Most certainly, in the person of Tony Blair. The Labour leader is in many respects an identikit US neo-con. Obviously Britain, unlike America, doesn't have the power to reshape the world. Nor is Mr Blair as unabashedly pro-Israel as Mr Bush. But he is a left-of-centre politician who espouses a robust and ideals-driven foreign policy, despite being fully aware of the unpopularity of his chief ally, and of UK domestic opposition to the neo-cons' main policy, the invasion of Iraq. If that isn't neo-conservatism, what is?

Has neo-conservatism proved successful in practice?

Yes...

* The neo-cons have to their credit the expulsion of Saddam from Kuwait, and the defeat of Slobodan Milosevic in Bosnia and Kosovo

* The "war on terror" has largely destroyed al-Qa'ida - or at least its capacity to strike directly at targets on US soil

* It cemented Republican dominance in the battle of ideas in the US, and helped the party win the elections of 2002 and 2004

No...

* Neo-conservative policies have led to a geo-strategic disaster for the US in Iraq and, possibly, in Afghanistan

* It is responsible for a worldwide surge in anti-Americanism, giving the impression the US did not care what anyone else thought

* It inspired the US tilt towards Israel which has made a settlement of the Palestinian dispute all but unimaginable