You did not have to look far this past fortnight for criticism of Barack Obama's handling of the crisis in Syria, but perhaps the Republican Senator Bob Corker has been the most evocative. ''It's like watching a person who's caged, who's in a trap and trying to figure a way out,'' he told The New York Times.

Obama has been described as tentative at best, feckless at worst. In support of the diplomatic course he has plotted, his allies have resorted to praising its agility.

The acerbic centrist Joe Klein wrote in his Time magazine column that the President's performance ''has has been one of the more stunning and inexplicable displays of presidential incompetence that I've ever witnessed''.

On the face of it, Obama has given his critics a wealth of material to work with, first by saying the use of chemical weapons in the Syrian civil war would constitute a ''red line'' in his thinking, then by declaring that the red line was the world's. By threatening unilateral action against the Assad regime and having Secretary of State John Kerry make a speech defending such a course, then - having lost British support - by requesting congressional authority.

(It has been reported that some in Congress who called for Obama to turn to them have since confessed they would have preferred it if he had just fired his missiles and been done with it.)

When it became clear that he might not win the support of the Democratic-controlled Senate, let alone the Republican dominated House of Representatives, Obama was left with no good options.

Then came the press conference in which Kerry was asked if there was anything Syria could do to avoid a strike. Well yes, he responded, Syria could give up all its chemical weapons. This was apparently an example of Kerry ''going freelance'' rather than expressing US foreign policy. Kerry suggested so seconds later when he added ''that's not going to happen''. And not long after the press conference the State Department issued as statement confirming Kerry was simply making a rhetorical point.

At this point the White House appeared to lose control of events. The Russians leapt at the proposal, contacted their Syrian ally and went public saying such a course of action might work. British Prime Minister David Cameron, who had already been neutered by his own Parliament, made positive noises about the option. Then Ban Ki-moon, Secretary-General of the United Nations - which, neatly enough, had already been neutered by Russia's veto in the Security Council - leapt aboard the peace train too.

Without foreign or domestic support for a strike and having already turned over his own authority to a Congress with the lowest approval rating in history, Obama had little choice but to embrace a plan conceived largely in Moscow and Damascus. A spokesman said the President was willing to ''take a hard look'' at the proposal. Despite the administration's scepticism, Kerry is now in the midst of these negotiations.

So how did this happen? How did a President willing to approve a military surge in Afghanistan, an incursion into Pakistan to kill Osama Bin Laden and an ongoing program of drone strikes become so tentative?

In part, says a former Clinton adviser and senior fellow at the Brookings Institution, Bill Galston, Obama is captive of a force larger than himself, an ''Iraq syndrome'' that grips the entire American polity, just as America suffered a Vietnam syndrome in the decade after that war. After Vietnam, Americans elected a president they viewed less prone to military adventurism in Jimmy Carter.

In his book The Icarus Syndrome another prominent DC pundit Peter Beinart broadens this argument, saying that American hubris is cyclical and has been for generations. Post-Vietnam confidence in America's might can be seen as resurgent about the time President Bill Clinton launched his bombing campaign in Kosovo, expanding in the first Gulf War and reaching its zenith in Iraq.

With the pendulum reversed, Galston says, Obama was elected on the promise that he would behave as a peacemaker rather than a warrior. So far, Galston notes, he has kept up his end of the bargain. His use of military has either been designed to speed disengagement - the surge - been without risk to American personnel - the drone strikes - or clearly targeted and defined - the killing of Bin Laden.

Indeed, Obama said as much in his press conference at the G20 in St Petersburg last week. ''I was elected to end wars, not start them. I spent the last 4½ years doing everything I can to reduce our reliance on military power as a means of meeting our international obligations and protecting the American people.''

But over the course of his presidency Obama has not prepared the US for the painful truth that engagement and disengagement is not only a function of US foreign policy, but of unfolding geo-strategic circumstance, Galston says.

He says America's Iraq syndrome has already led to a power vacuum in the Middle East. This, he says, could have profound consequences. If Israel ceases to believe America's pledge of military support should it be attacked, that mistrust will have an effect on how it decides to act on Iran's nuclear program.

All this brings us neatly back to Russia and its President, Vladimir Putin, who has not only succeeded in taking the lead in diplomacy over Syria, but who stunned DC this week by lecturing it from The New York Times' opinion pages on the dangers of American exceptionalism.

And Putin's piece had some gall. ''We need to use the United Nations Security Council and believe that preserving law and order in today's complex and turbulent world is one of the few ways to keep international relations from sliding into chaos,'' he wrote.

''Under current international law, force is permitted only in self-defense or by the decision of the Security Council. Anything else is unacceptable under the United Nations Charter and would constitute an act of aggression.''

Handy, then, that Russia has used its veto in the Security Council to prevent the UN's primary peace-keeping authority from even issuing a censure against Syria.

Then Putin took issue with Obama's invoking of American exceptionalism in urging action on Syria in his speech on Tuesday night.

''America is not the world's policeman. Terrible things happen across the globe, and it is beyond our means to right every wrong,'' Obama said. ''But when, with modest effort and risk, we can stop children from being gassed to death, and thereby make our own children safer over the long run, I believe we should act. That's what makes America different. That's what makes us exceptional.''

Putin scolded in his opinion piece: ''It is extremely dangerous to encourage people to see themselves as exceptional, whatever the motivation.''

The idea of American exceptionalism was written into the nation's DNA when the founding fathers declared in biblical tones that America, uniquely, was to be founded on the principals of equality and human rights.

American liberals have always had an uneasy relationship with exceptionalism, especially so since neoconservatives used it as the intellectual justification for the invasion of Iraq. Asked if he believed in exceptionalism Obama himself once responded: ''I believe in American exceptionalism, just as I suspect that the Brits believe in British exceptionalism and the Greeks believe in Greek exceptionalism.''

The far right in America has never forgiven him for the comment, claiming it as evidence of his lack of patriotism. They might be surprised to learn that it was Stalin who coined the term to explain the American proletariat's revolutionary reluctance.

Galston sees evidence for Iraq syndrome in the rise of isolationism in America's far right, in the moderate right's reluctance to use force to defend strategic interests, and in the reluctance of the Democratic left to take military action to defend human rights. He also sees it in the polls that show while America believes Obama's assertion that Assad killed nearly 1500 civilians with chemical weapons, they believe it is neither in their interest not is it their responsibility to use their armed forces to ''degrade and deter'' him.

Not everyone welcomes this new mood. In a Los Angeles Times opinion piece this week, Professor Timothy Garton Ash, of Oxford and Stanford universities, wrote: ''To the many critics and downright enemies of America … I say only this: If you didn't like that old world in which the United States regularly intervened, just see how you like the new one in which it does not.''