Fragile and limited in its stated goals as it is, the Gaza ceasefire due to start at 6am today is potentially the most positive development in the Israel-Palestinian conflict for a long time. And not only for the respite it will bring on both sides of the border. If it becomes entrenched, it will stand as a considerable diplomatic achievement for Egypt, which brokered the deal. Ehud Barak, Israel's Defence Minister, also deserves congratulation. Having in several ways cast himself as a hawk in the past year, he had the good sense and courage to withstand, at least for now, the clamour from several other ministers for a full scale military invasion of Gaza. Such an operation would have – and still may if the truce breaks down – risked perhaps hundreds of Israeli lives and thousands of Palestinian ones, and probably for no easily measurable gain. There may still be those in Israel's political establishment who see this as a way of proving that everything had been tried before an invasion which many in Israel still purport to think inevitable. But the hope must be that Mr Barak has had the maturity to see, first that the chances of eliminating Hamas by military means are negligible, and secondly that public opinion may not, after Lebanon, so easily tolerate again rapidly rising loss of life without bankable results.

The ceasefire is, foremost, a crucial test for Hamas who have shown scant regard for the impact of the rocket attacks not only on the beleaguered Israeli communities of the Gaza periphery but also on the Palestinians themselves, who have suffered perhaps twenty times as many civilian casualties from Israeli counter-attacks. It now has to use its tightened control in Gaza to police the armed factions – including the most unruly and self-interested – to ensure that it is not breached. But it is a test for Israel as well, having blamed Hamas's undoubtedly destructive attacks on the crossings, it surely cannot resist pressure to start opening them if these now stop. It will need to resist temptations posed by short-term internal politics to find an excuse to breach the ceasefire itself. And it may have to contemplate much more far-reaching exchanges of prisoners if it is to secure the long overdue return of Gilad Shalit, the Israeli corporal taken hostage by Gaza militants two years ago.

The fragility of the ceasefire can hardly be overstated. But the opportunities it presents cannot be overstated either, not least for a more, albeit cautiously, pragmatic approach to Hamas, both in Israel itself and in those European countries which have for the last year allowed Israel, and a discredited US administration, to shape its policy in the Middle East.