Scowcroft (C) with President Bush (L) and White House Chief of Staff John Sununu in 1989. (Wikipedia.)

Today marks the 90th birthday of America's leading foreign-policy strategist of the last 40 years. No, not Henry Kissinger or Zbigniew Brzezinski, who served as national security advisers to presidents Richard Nixon (1969-75) and Jimmy Carter (1977-81) respectively. I am referring to Brent Scowcroft, who served in the same position for presidents Gerald Ford (1975-77) and George HW Bush (1989-93).

Mine is hardly an isolated view. A new biography, Bartholomew Sparrow's The Strategist: Brent Scowcroft and the Call of National Security, reaches the same conclusion. Most of the American reviewers of the book agree (see, for instance, Jacob Heilbrunn in the March-April issue of The National Interest) National security advisers to both Republican Ronald Reagan and Democrat Barack Obama have praised Scowcroft as a role model.

Why is this case? Why should we recognise Scowcroft as the most distinguished US foreign policy figure of modern times?

Well, for one thing, he was widely regarded as a calm, sober, judicious, loyal, non-partisan and highly intelligent strategist. A master of the day-to-day process of coordinating Washington's bureaucracies and an honest broker in high-level deliberations, he was scrupulous about presenting different arguments to be widely debated among policymakers. Scowcroft was also something of a rare exception in a town like Washington: he lacked the insatiable drive toward power and celebrity.

For another thing, there's his record in the Bush Sr Administration. Let me provide three examples: Russia, China and Iraq.

Russia

With the end of the Cold War and the demise of Soviet communism, Scowcroft rejected triumphalism in favour of caution. Far from maximising American advantage, he was focused on managing the collapse of an empire lest it unleash the kind of instability, chaos and bloodshed usually associated with the fall of empires. That is why Scowcroft helped negotiate the end of the Cold War to the advantage of both the Soviets and the Americans. It is also why he did not push for NATO expansion in the 1990s, lest it upset the strategic sensibilities of a nuclear great power.

China

Following the Tiananmen Square massacre in 1989, Bush secretly dispatched Scowcroft to Beijing to maintain official contact with a Chinese leadership slipping into dangerous isolation. At the time, Bush and Scowcroft were accused of 'kowtowing' before the communists. In reality, as Democrat China hand Michel Oksenberg remarked at the time, 'it was an act of courageous statesmanship.' While Democrats and many Republicans appeared willing to risk isolating China's government and to court its animosity, Scowcroft was salvaging a constructive relationship with the most populous nation on earth. In the process, he prevented a situation that could have easily become worse: a more oppressive China at home and a troublesome China abroad.

Iraq

After Saddam Hussein's invasion of Kuwait in August 1990, Scowcoft took the lead in organising the US-led multinational response. According to The Economist, the Gulf War was 'Mr Scowcroft's finest hour.' He was, to be sure, criticised for not intervening when the Iraqi tyrant began slaughtering Shia and Kurds after the US-led liberation of Kuwait. But the goal, as Bush and Scowcroft always made clear, was never to take out Saddam or democratise Iraq; it was about restoring order and stability to that part of the world.

Like most realists, Scowcroft believed that although containment – sanctions, naval blockades, no-fly-zones – may have lacked the political sex appeal of 'liberation', at least it would avoid the unintended consequences of a liberated Iraq. Look at Iraq today and you can see what he meant: high costs in blood and treasure, a Shia ascendancy along with strengthened Iranian power and influence in Iraq, and marginalised Sunni Iraqis who turned to an insurgency that has morphed into a plethora of jihadist groups.

That is why, in the post-9/11 era, Scowcroft emerged as the leading critic of the Bush Jr doctrine of preventive war and democracy promotion. In a famous Wall Street Journal op-ed in August 2002 titled Don't Attack Saddam, Scowcroft warned of the dire consequences of an invasion of Iraq. Toppling the Sunni regime, he argued, would 'swell the ranks of the terrorists' and 'might destabilise Arab regimes in the region.'

Scowcroft didn't make these criticisms lightly. After all, he was President Bush Sr's best friend and he mentored Bush Jr's national security adviser Condi Rice. He copped criticism for speaking out against the war, but his warnings were prescient.

Which brings me to what distinguishes Scowcroft from other leading US foreign policy figures in the modern era: his realism (Kissinger is also widely seen as a realist, but almost all American realists opposed the wars in Vietnam and Iraq; Kissinger did not). According to foreign policy realists, and contrary to the liberal interventionists on the Left as well as the neo-conservative crusaders on the Right, America is not a 'new Israel' but one nation among others and should be guided by national strategic and economic interests, pursued with a pragmatic calculation of commitments and resources. Its goal should not be to impose its democratic ideals on other nations but to secure peace and stability through maintaining a balance of power among potential adversaries. Not for realists any noble, grand causes to transform the world in a democratic image.

It is fair to say that realism has provided a sound alternative to the excesses of American idealism, whether it was over-extension in Vietnam or aggressive unilateralism and democracy promotion in Iraq. But realism, with its antecedents in 19th century balance-of-power politics, is hardly perfect (what strategy is, in a messy world?). During the Cold War, realists downplayed the inherently evil nature of communism; in the 1980s Scowcroft dismissed Ronald Reagan's worldview as simplistic, wincing in 1987 when the Gipper called on Mikhail Gorbachev to 'tear down' the Berlin Wall. Even Sparrow, in his otherwise sympathetic biography, says Scowcroft and the Bush team were 'unable to offer Americans a vision of a transformed world.'

Still, realism in the hands of Scowcroft and his Bush Administration colleagues James Baker, Lawrence Eagleburger and Colin Powell was an important corrective to the fog within which Wilsonian idealism and a Pax Americana has shrouded US public discourse since the end of the Cold War.

Scowcroft's 90th birthday today also marks the 12th anniversary of the US-led invasion of Iraq. We are still living with the consequences of what the historian Tony Judt called 'the worst foreign policy error in American history.' But Washington policy makers could do worse than heed Scowcroft's counsel about the importance of allies, the danger of hubris, illusions of omnipotence and the wisdom of limits, restraint and modesty in a world that does not conform to American expectations.