Ceasefires are always a fragile arrangement. So much can go wrong that some last barely beyond the announcement, and others produce a spike of bloodshed as they end. The agreement of a four-day cessation of violence in Syria's increasingly savage civil war must therefore be a matter for prudence.
But it is a considerable achievement for the United Nations envoy, nonetheless. Lakhdar Brahimi has managed to secure tentative agreement where both Arab League observers and the former UN Secretary-General, Kofi Annan, made no progress.
The failure of Mr Annan, a skilled and emollient diplomat, was cue for widespread despair in the international community at the apparent intractability of the conflict in which at least 20,000 people have been killed since the uprising began in March 2011.
That both President Bashar al-Assad's government and most of Syria's opposition groups appear to back the truce says much about the skill of Mr Brahimi. It appears that a background in both Arab and French diplomacy has left the former Algerian independence fighter with a clearer sense of what might work in Syria, and perhaps also assisted his efforts to contact a wider range of rebel factions than his predecessors managed.
Indeed, Mr Brahimi's more sophisticated approach is most obvious in his choice of this week's Muslim holy weekend of Eid al-Adha as the starting point for the proposed ceasefire, making the most of both the religious overtones of the festival and also its finite timescale.
Nor is the UN envoy's progress on the ground in Syria his only success. His moves have also received support from Moscow and Beijing, which have previously repeatedly vetoed UN Security Council resolutions condemning the Assad government's role in the conflict. The latest plan to kick-start political reconciliation may, of course, come to nothing. But to have come this far is still a significant advance.