Syria crisis: Can UN mission succeed?
Will the new acronym UNSMIS - the UN Supervision Mission in Syria - pass into the Middle East's lexicon and take up its place alongside those of other deployments, such as UNTSO and Unifil, which have for decades been helping keep some of the region's potential flashpoints from exploding?
Or will the mission collapse and withdraw in disarray, unable to carry out its task of monitoring compliance with an already highly compromised ceasefire, and with chief envoy Kofi Annan's six-point plan for stabilising the country and fostering dialogue on its future?
The Americans and others are clearly sceptical, and have already warned that their support for a renewal of the mission, when its initial mandate expires in three months' time, should not be taken for granted.
It is certainly unlike any other peacekeeping mission the UN has embarked on in the Middle East, and possibly anywhere else.
Normally it is a case of monitoring respect of a formal truce involving states, not trying to ensure compliance with a work-in-progress peace plan in a situation which in some ways resembles a civil war.
In other words, the observers are being expected to help create the peace they are supposed to be monitoring.
Mr Annan himself has said the Security Council's decision to deploy 300 unarmed UN monitors is "a pivotal moment in the stabilisation of the country".
That is certainly what he hopes: that the presence of the monitors will in itself help to bring the situation under control, by "changing the political dynamics on the ground", as his spokesman Ahmad Fawzi put it.
It is clearly a gamble, a last throw of the dice for a political solution to the Syrian crisis.
It is hard to imagine any other peace project being more balanced and reasonable than the Annan plan, or garnering the unanimous international support that he has marshalled behind it.
So if this does not work, nothing will. It will be back to a trial of strength on the ground, with predictably drastic consequences.
Despite the obvious imperfections of the ceasefire, to put it mildly, the prognosis for the observer mission is not totally black.
Violence has flared and sputtered in many places. But overall the levels of hostilities and the casualty figures are below pre-ceasefire averages.
The tiny number of observers already deployed as the advance party have covered a surprising amount of ground, especially considering that they are also engaged in setting up liaison mechanisms with both sides and organising logistics for the full deployment.
There have been several instances in the past few days - in Hama and Douma, for example - where visits by the monitors have taken place peacefully, only for violence to erupt again the next day.
In both instances, the monitors returned later to verify what had happened.
But in Homs, where two observers are now permanently stationed, the casualty figures are no longer topping the nationwide lists as they did day after day before the monitors arrived.
The heavy weapons which wrought such carnage seem to have been more or less silenced there.
So the deployment of the full 300-strong contingent over the coming weeks should have a considerable impact.
They will obviously split down into small groups, and - presuming they get the freedom of access and mobility the UN has demanded and been promised - they should be able to move swiftly from one trouble-spot to another as required.
Their task is not just to monitor compliance with the truce, but to ensure that all clauses of the Annan plan are fully implemented.
Most crucially, that means verifying regime compliance with the provision that it must withdraw its troops, tanks and heavy weapons from population centres.
According to Mr Fawzi, Syrian Foreign Minister Walid al-Muallim has informed Mr Annan in writing two days ago that those provisions have already been carried out - despite much evidence to the contrary.
But the commitment is there, which means that confronting the authorities with evidence of breaches should in theory lead to their swift correction.
Much will depend not just on the regime's intentions, but on those of the various armed opposition groups.
Once fully deployed, the UNSMIS monitors should be able to gauge the validity of the regime's assertions that the post-truce violence has been provoked by the rebels - a contention strongly backed by Russia.
If either side, or both, decides to keep up the violence, the observers might ultimately face no choice but to withdraw, especially if the unarmed monitors start taking casualties.
But if the regime is clearly seen to be to blame, and consistently out of compliance with agreements it has signed, the consequences would be considerable.
Russia, China and others who have protected Syria from punitive action by the Security Council would find themselves perhaps unable to continue doing so.
It is doubtful that Damascus can go it alone, especially without Russia.
If the Russians themselves remain as committed to the Annan plan as they say they are, and the rebel side complies, the regime may have no choice but to implement steps - such as freeing all detainees and allowing demonstrations to be held unhindered - that would threaten its grip on much of the country and weaken its position in any settlement dialogue.
Some Arab analysts in touch with regime thinking believe it does understand that there will be a price to be paid for survival in any form - perhaps the formation of a government with opposition figures prominent in it.
But many obstacles will have to be overcome on the ground before events reach anywhere near that point. And given the fate of the ceasefire so far, optimism is in short supply.