In May, Lebanon was plunged into a civil war of sorts as Hezbollah’s forces went on the offensive against the legitimate government. But regardless of whether the party can impose its will on the people, this month or next, very soon at any rate, a rare institution of huge importance to Lebanon will officially begin operating in Leidschendam, a suburb of The Hague. The United Nations and Lebanon are finalising preparations for a tribunal to indict those responsible for the 14 February 2005 assassination of the one-time Lebanese prime minister, Rafiq Hariri. Once this phase is completed, all that will be needed before the trial begins is a formal legal accusation, which should come by the end of this year.

It’s not often that political murders are punished in the Middle East. Hariri’s killing triggered what became known as Lebanon’s “Cedar Revolution”, where hundreds of thousands of people took to the streets for three months demanding that Syria withdraw its army and intelligence agents from their country, after a 29-year presence. Syria’s regime is the only serious suspect in the crime — a fact recognised early on by UN investigators who have spent three years preparing a file on the Hariri case for the Leidschendam trial.

There seemed to be a neat finality to the Cedar Revolution when Syrian soldiers left Lebanon in April 2005. It was an illusion. Since then the Syrian president Bashar Assad has sought to reimpose hegemony here, in the hope that he can one day order his army back. Syria, with Iran, played a key role in the May coup attempt by Hezbollah and its allies. It is Syria, almost certainly, that has been behind dozens of bombings and assassinations in Lebanon and the slaying of several of its political foes. Damascus has also blocked a scheduled presidential election, imposing a potentially dangerous political vacuum.

Assad is sending two plain messages: nothing can be done in Lebanon without his priorities being considered. And more explicitly, Syria will not allow normality in the country until the tribunal issue is resolved to its satisfaction — meaning that some baroque deal is agreed, possibly along the lines of the Lockerbie arrangement with Libya, to spare the Assad regime blame for Hariri’s killing.

The most disturbing aspect of this blackmail is how few opinion-shapers in the West feel outraged enough to condemn it, let alone grasp what is at stake in the Hariri tribunal. Here is a unique opportunity to hold murderers accountable for a political crime, and yet an increasing number of Western politicians, pundits and researchers are finding nice things to say about Syria, advocating its “engagement”, unconcerned about what it has done and continues to do in ­Lebanon.

Take the author William Dalrymple. In October 2007 in the Spectator, he defended the Syrian regime on the grounds that it gives “minorities a security and stability far greater than anywhere else in the region. This is particularly true of Syria’s ancient Christian communities.” His article would have been more persuasive if it had mentioned the cheerless fate of the majority in Syria, even as it missed how the status of a prominent minority, the country’s 1.5 million Kurds, leaves much to be desired. Or he could have mentioned how harmful the Assad regime has been to the most assertive and independent of Middle Eastern Christians, those in Lebanon, marginalising them and killing two Christian presidents who threatened Syrian supremacy. Dalrymple accepted that Syria was repressive, but forgot to laugh when adding that it is “a police state that tends to leave its citizens alone as long as they keep out of politics”.

There was also Dalrymple’s descent into urbane cynicism. He argued that “the Middle East is not a place where simplistic notions of Good Guys and Bad Guys make much sense. It is a place of murky moral greys.” That won’t change with observers as indulgent as Dalrymple. But when he published his piece the Hariri tribunal had already been put on track. In Dalrymple’s shifty paean to the Assads, in his resort to moral relativism, he ignored the fact that the UN was creating a venue that might help sharpen some of the “moral greys”.

But Dalrymple was hardly alone. In the United States in particular, acrimony towards the Bush administration has prompted critics, in a Pavlovian reflex, to demand an overhaul of everything the administration has stood for, including Syria’s isolation. Among those favouring engaging with Damascus are influential institutions such as the Carnegie Endowment for International Peace, the New America Foundation and the International Crisis Group, as well as Barack Obama and, to a lesser extent, Hillary Clinton.

In their statements on Syria, most of the “engagers” , intentionally or not, have downplayed the significance of the Hariri tribunal as a revolutionary innovation in the area. Far from considering issues of principle, few have addressed how dialogue with Syria might terminate Lebanon’s fragile sovereignty, while some of them have favoured accepting a return of Syrian “influence” over Lebanon.

What are the practical implications of this? No one seemed to notice that Zbigniew Brzezinski, now an Obama adviser, was in Dam­ascus last February when the Hezbollah official Imad Mughniyeh was assassinated in the Syrian capital. How ironic, yet so very typical, that a prominent engager like the former US national security adviser would find himself chatting up a regime at the very moment it was caught hosting a man wanted worldwide for killing innocent civilians.

That is why the Hariri tribunal is so vital. It might not only make Arab regimes think twice before resorting to murder; it might also instil a modicum of moral fibre in their complaisant collaborators in the West.