There is a dangerous false assumption at the heart of the West's negotiations at, and reporting of, peace talks in Minsk over the fighting in eastern Ukraine. It is that Russia wants to have direct control over a small area of Ukraine – about 3 per cent of the country; the area, slightly smaller than Kuwait, now under separatist rule – and that Ukrainian forces are fighting to win this area back.

You can't blame Western negotiators or journalists for thinking this is what is going on, because it's what the Ukrainians are bound to tell them. That doesn't mean it is the underlying truth. The evidence so far is that what Russia actually wants is indirect influence over the whole of Ukraine, and for the West to pay for it.

President Petro Poroshenko of Ukraine cannot admit this publicly; he would find it hard to admit it privately. But Ukraine lost the war to keep the far east of the country last summer, in a little reported series of battles on the frontier. Ukrainian border guards, and troops trying to enforce control of the border, came under massive artillery barrages from the Russian side of the border. They couldn't fire back into Russian territory without inciting a full-scale Russian military assault. Accordingly they were massacred, or they surrendered, or they ran away.

Ever since, a large section of the border has been under Russian-separatist control. As long as Ukraine can't lob shells into Russia, and Russia is prepared to lob shells into Ukraine, that is how it will stay.

The Ukrainian army and volunteer units have been fighting a war of containment, in two parts. One is military: stop the separatists breaking out into a wider area. Another is political, psychological and economic: create effectively a new border between Kiev-controlled and separatist-controlled Ukraine, disavowing any responsibility for pensions or essential services there, giving up any attempt to collect taxes, accepting the separatists' rejection of Kiev-organised elections.

Seal the rebels off, in other words, not in the hope of reconquering the territory later, but in acceptance of the loss, and on the assumption that the cost of repairing the damage and looking after its pensioners and subsidised coal mines would fall on Moscow.

That was the deal Kiev thought it had at the end of last summer: a frozen conflict, an eternal ceasefire, in a zone along the lines of Abkhazia and South Ossetia in Georgia, Transnistria in Moldova, Nagorno-Karabakh in Azerbaijan, North Cyprus and, indeed, Crimea.

Even the recent upsurge in fighting, which has been in so many obvious ways a series of defeats for the Ukrainian government (they have lost the ruins of Donetsk airport, seen the rail and road junction at Debaltsevo almost encircled, and struggled to hold their lines along the Kalmius and Severny Donets rivers), could be seen in the bigger picture as a victory for Kiev. Separatist forces, including Russian citizens, have had to pay a terrible price in blood and maiming for every foot of ground they have won; and they are a long way from controlling the towns they held at the high-water mark of their rebellion, let alone the whole of Donetsk and Lugansk regions. And Ukrainian defenders have achieved this without Western weapons.

It is not something any Kiev politician could say openly, but Ukrainian government forces – the forces fighting in support of the ideal of Ukraine as an independent European country – have not been fighting on friendly ground. They have not been fighting to win the Donbass. They have been fighting to stop the fighting spreading west to Kharkiv and the great cities of the Dniepr – Zaporozhye, Dnepropetrovsk and Kiev itself – because they have no way of knowing that Putin has decided to leave them alone.

Do the people of central and western Ukraine, even Russophone southern Ukraine, actually want the Donbass back? I'm not sure. Do the people of Donbass want to return to a country whose forces have rained artillery shells down on them (no more, to be fair, than have rained in the opposite direction)? I doubt it.

Putin and his inner circle know that if the conflict were frozen along present lines, what would appear to be a victory for his ruthless willingness to use force would actually be a defeat. He would add another tiny, needy enclave to his collection; Russia would be stuck with the bill; the rest of Ukraine would be lost to him entirely; sanctions would continue.

Hence his current strategy: to create a puppet state, a region that is both a Russian protectorate and part of the Ukrainian body politic; over which the majority of Ukrainians have no real control, but which has powers to shape Ukrainian national policy, and which the majority of Ukrainians are obliged to pay to rebuild. And since Ukraine is, financially, dependent on the West, it is the West that would pay.

The most important thing is that the fighting should stop, to put an end to the killing and to give some relief and security to the millions of people trapped in the war zone, many of them cold, hungry and without light. Any deal that silences the guns is good in the short term.

But to stop the war permanently will be much, much harder. It demands a recognition that for all the Kremlin's lies, there is a genuine separatist movement in eastern Ukraine. It demands an acceptance that a frozen conflict is likely to be more amenable to Ukrainians on both sides of the ceasefire line than an attempt to shoehorn the rebel enclave back into a country nominally under Kiev's control. It demands a Ukrainian culture that finds a way to combine the dissonant histories of its nationalist and neo-Soviet nostalgists, its Ukrainophones and Russophones, its Greek Catholic and Russian Orthodox believers. It demands Ukrainian will and Western help for reform. And it demands a wiser, less frightened leader in the Kremlin. In that sense, Angela Merkel's instinct is right. Putin's unnecessary war is unjust. Freezing the conflict might be seen to reward aggression. But if it buys time for independent Ukraine to thrive, and Putinism to wither, it will have been worth it, for Russians as much as for Ukrainians.