The cease-fire in Ukraine appears to be holding, for now. This despite reports of shelling from both sides and talk from the EU that new sanctions on Russia will be announced on Monday. Many people seem convinced that the truce is bound to fail, and why not? Ukraine has said that it will not recognise the “terrorist” statlets or the annexation of Crimea, and the rebels in Luhansk and Donetsk have said the beginning of a peace dialogue will not deter them from seeking eventual independence. The truth is, however, that for the moment peace suits everyone.

Despite their stunning victories in recent days, most of it achieved by the now almost universally accepted presence of Russian regular troops, until two weeks ago the rebels were on the rack. They had been forced back into two small and separated enclaves by the Ukrainian army, had lost control of both Luhansk and Donetsk airports and with mounting casualties they faced imminent defeat. Only deliveries of Russian heavy weaponry and “volunteers” were keeping them going. Russian intervention has saved them for now, but there is no guarantee beyond Vladimir Putin’s personal calculations of a western response that it will be maintained.

Mr Putin meanwhile, appears set to come out of this most recent crisis as the major victor. He took the extreme risk of committing Russian troops to what amounted to a covert, but nonetheless outright, invasion of eastern Ukraine and looks likely to get away with it. His calculus, that western powers would offer strong moral and verbal support, but draw the line at committing troops to fight was entirely correct. Russia may face a new round of sanctions on key Kremlin individuals and industries (although this is by no means certain) but he is reasoning that Russia, and his regime in particular, can survive the short term impact of sanctions, and once they are repealed the situation on the ground will remain the same. Ukraine will not be ready to join NATO for a long, long while, and once the west has lost interest in the Ukrainian crisis, Russia will still be right next door. After all, geography is forever.

The NATO summit in Wales this last week was a strong display of unanimity by the alliance , and the presence of Ukrainian President Petro Poroshenko suggests that the western powers are prepared to support for embattled government. But this support is likely to have limits. NATO has committed itself to creating a new rapid reaction force “spearhead” for eastern Europe and has spoken strongly about Russian aggression, but it is clear no troops will be sent to fight. Quite sensibly, no one wants to provoke outright war with Russia over Ukraine and the alliance appears unwilling to breaks its treaty commitments from the 1997 agreement with Russia not permanently base troops in eastern Europe. I suspect that if the fighting does indeed cease, many members of the EU will hope for a quick reversal of sanctions in order to reduce the strains on their economies. It took France until Russia sent troops into Ukraine to “suspend” delivery of the Mistral warships it is building for the Russian navy, and they for one will be eager to avoid the EUR 1.4bn hole cancellation will create in the French budget.

Which brings us to the real loser under this cease-fire, Mr Poroshenko and Ukraine. To go in the space of weeks from near victory to a humiliating agreement which leaves the separatists empowered and Russia emboldened is a serious blow. But I can’t see that he had much choice. The Russian invasion was devastating, and while casualty figures have not been announced, eyewitness accounts speak of a shattering defeat for the out-gunned Ukrainian military which lost a sizeable number of armored vehicles and artillery. Barring outside help Ukraine faced total defeat. Ultimately, like in Georgia in 2008, no-one came to save them in this crucial hour. Moreover, despite IMF and EU support for the Ukrainian economy, the task of reforming it is colossal and the immediate survival of Mr Poroshenko’s government depends on extensive economic links with Russia, especially gas deliveries. These remain under negotiation despite the recent surge in fighting. Without an agreement, Ukraine could be forced to pay an extremely high and destabilising price or, worse, face a cut off altogether. To borrow an expression, winter is coming.

So the cease-fire remains in everyone’s best interest for now. That is not to say it will hold. Too often such agreements are brought down by the situation on the front lines and a quick escalation from an exchange of shelling to a total resumption. But this agreement reflects pragmatism on the part of the Ukrainian government, which realises its current geographical, economic and political status depends on coming to some sort of agreement with Russia. I cannot see them breaking it. No assurances about the rebels, their calculation is entirely different, although if Mr Putin keeps a tight hold on them, it is in his interest to maintain the truce as well. Russia’s position depends on its intervention being short. The last thing it needs is an open ended conflict in Ukraine and further sanctions on its already anaemic economy.

The next week will be crucial for both sides.