Last Sunday, US Senator John McCain offered a bleak assessment of the situation in Syria. He observed that the president, Bashar Al Assad, "now has the upper hand and it's tragic while we sit by and watch". Mr McCain's sense of outrage is shared by very few others in the United States, as those willing to advocate American intervention in Syria on moral grounds have been largely silent.

Things were different when President George W Bush prepared to invade Iraq. He had the support of a group of moral interventionists who endorsed the removal of Saddam Hussein, as they had earlier backed American involvement in the Bosnia war. Most of these individuals were public intellectuals, writers and academics who had little ideological affinity with the Bush administration. Many came from a left-wing background, earning them the label liberal hawks.

Yet the silence of most of these individuals on Syria has been so noticeable that the Washington Post's Jason Horowitz wrote about the topic last week. He speculated that the liberal hawks had been spooked "by the traumatic experiences in Iraq and Afghanistan and the clear reluctance of a Democratic president to get mired in the Middle East. Call them Syria's mourning doves".

Certainly, American fatigue after a decade of conflict in the broader Middle East is a major factor in shaping responses to Syria. However, moral interventionists generally base their actions on principle, and principles aren't supposed to change depending on political context. That is why there appears to be a more profound reason for the silence of the interventionists, and it probably has something to do with culture, even if few of them might readily admit to this.

Justification for American interference in Syria must be based on a narrative that appeals to the American public and politicians. The narrative in Bosnia stressed how Washington had to assist a freedom-loving people repressed by brutal Serbian forces, who had abused the human rights of defenceless Bosnian Muslims.

After the massacre of thousands of Bosnian Muslims in Srebrenica in July 1995, President Bill Clinton escalated America's military role in the Balkans, allowing it, ultimately, to sponsor the Dayton Accords that ended the Bosnian conflict. This diplomatic success through armed force validated the attitudes of the moral interventionists.

Iraq was less convincing. The outcome of the war seemed too messy to fit into the neat narrative that the liberal hawks had defined before the war. Yes, Saddam Hussein was a leader of unspeakable viciousness, ruling over a long-suffering population. But what emerged from the American invasion was less a people welcoming their new-found freedom than a society falling back on the primary identities of sect or tribe as Iraq descended into chaos.

For the liberal hawks, there was little liberalism around which to rally. Armed Islamist organisations gained the upper hand. Al Qaeda found a new impetus. Iran benefited the most from the changed situation. And for a long time political violence and factionalism were the order of the day, so that many interventionists wondered whether they had not made matters worse by pushing for action in Iraq.

Given the memory of the September 11, 2001, attacks, this had a freezing effect on American moral interventionists. After all, liberty and democracy were regarded by them as necessary antidotes to the religious extremism that had led to that day. Instead, what materialised in Iraq, and is now materialising in Syria, was an Islamist upsurge accompanied by heightened sectarianism, precisely the opposite of what the interventionists had sought.

There is something else. As the one-time interventionists watch events in Syria, what they can see is that the uprising has tended to be led by a rural population, while Syria's more polished and cosmopolitan urban population has tended to be ambiguous. Indeed, the Assad regime has played on this urban-rural dichotomy to divide Syrians. Many in the secular west find it difficult to identify with rebels who shout "God is great" at every turn, and who come across as unsophisticated and frequently uncontrollable.

Syria's rebels often appear too different from Americans, unlike the Europeanised Muslim Bosnians and Kosovars, to invoke much sympathy in the United States. Their fight seems so plainly not to be America's fight that moral interventionists have little room to make a case on their behalf, especially in a country that has turned in upon itself and embraces the Obama administration's minimalism abroad.

That is not to say that there are no supporters of American intervention in Syria, or those who don't recognise the serious political implications of President Barack Obama's refusal to do much there. Vali Nasr, a former Obama administration official and the dean of the Johns Hopkins School of Advanced International Studies in Washington, DC, has been critical of the president's performance in Syria, publishing his thoughts in an excellent book, The Dispensable Nation. So too has another former Obama administration official, Anne-Marie Slaughter, who teaches at Princeton University.

Leon Wieseltier, the literary editor of The New Republic, has been equally disparaging of Mr Obama's indifference towards the loss of life in Syria. "The moral dimension must be restored to our deliberations, the moral sting, or else Obama, for all his talk about conscience, will have presided over a terrible mutilation of American discourse: the severance of conscience from action," Mr Wieseltier wrote.

Yet individuals such as these are exceptions. Their willingness to challenge the trend of apathy in the United States is laudable, as is their worry that America will pay a price, both strategic and moral, for avoiding Syria. They also realise that an America that abandons Syria cannot be true to the values it purports to represent.

Michael Young is opinion editor of The Daily Star newspaper in Beirut

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