This story was recently told to me by a diplomat who saw it happen. Ukraine, he said, was helpless: its army was then unable to offer serious opposition. David Cameron and Barack Obama chose to withdraw from the talks (saying they clashed with Day D celebrations in Normandy), so the talks were mediated by France and Germany instead. They let Putin staple things in a way that eased Kiev’s control over eastern Ukraine. This 2015 deal – known as Minsk II – is now being held in Whitehall as a reward for aggression and a case study into what is not allowed to happen now. But it can. The Russian invasion is going badly: its dysfunctional army is downing its own planes and has suffered more casualties in the first four weeks than the ten years of the campaign in Afghanistan. At least one million Ukrainians are now armed and forcing Russian forces to retreat. Russia’s net military defeat by Ukraine is now a realistic choice. Putin may conclude that he can not win and start negotiating while continuing the bombing. Volodymyr Zelensky may want to agree on a deal to end the suffering. The big fear in London is that this could mean terms of peace that are dangerously generous to the Kremlin. For the past two decades, Putin has managed to persuade European leaders to give him some ground to stop him from doing something even worse. It began with Georgia in 2008 when, after its invasion, Nicolas Sarkozy – then president of France – was left to mediate for peace. This time there was no fork on the table, but instead, Putin informed Sarkozy that he intended to hang Mikheil Saakashvili, the president of Georgia, “off the ball.” Instead, it compromised control of South Ossetia and Abkhazia. This is Putin’s book. It has gained influence and even control over parts of Moldova and Azerbaijan by deploying troops. After the annexation of Crimea in 2014, it suffered some slight sanctions. But it withdrew from the Minsk II talks, forcing Kyiv to relax control of the two Russian-speaking territories and making it virtually impossible for Ukraine to function as a cohesive state. The Kremlin has continued to equip rebels in eastern Ukraine who, over the years, have sparked a war that has claimed the lives of at least 13,000 people. Putin’s experience has taught him that Europe – dependent on its gas – usually gets any excuse to look the other way. That’s why Boris Johnson is determined that, this time, it should be different. The Prime Minister is interested in “deterrence through denial” (a phrase he continues to use in meetings) by which he means the creation of Ukraine into a military force with such high-quality equipment that Putin would not dare to invade again. Some in Whitehall even express the idea of the Kremlin paying compensation to Ukraine (Kyiv has set the cost at $ 565 billion so far). But for any of this to happen, Zelensky would have to play hard – and turn down any smaller offers Putin makes, prolonging the battle. And the murder. This is where things get tough. So far, the democratic world is united – it is impressive – in the need to help Ukraine defend itself. But when should the fighting stop? Here, the alliance is already disintegrating, as Zelensky openly admits. Some of his allies, he says, want peace as soon as possible, either for humanitarian or economic reasons, even if it means taking over Putin. It is suspected that Germany belongs to this category. Then come the liberal hawks, such as Poland and the Baltic states, who want to see the Kremlin visibly punished. In the final category, Zelensky places the allies who urge him to fight and – in his words – that “they do not mind a long war because it will exhaust Russia, even if it means the death of Ukraine and has the cost Ukrainian she lives”. This group now contains an astonishing number of Britons and Americans. As one senior diplomat puts it: “If you look at all the options, our strategic interest is probably best served in a long war, a quagmire that drains it militarily and financially, so it can not do it again.” There is little optimism in London about the prospect of regime change in Moscow. If Putin loses in Ukraine, he may well be ousted (even authoritarians tend not to survive such humiliations), but the Whitehall consensus is that he will probably be replaced by someone worse. The cost of the non-peace agreement would also be significant – both in the lives of Russians and in Ukraine. Britain and Poland are both pushing for tougher sanctions to stay across the country, not just the oligarchs. This is not something that ministers are openly discussing, for obvious reasons: it would mean that the misery of the 140 million Russians who are already suffering greatly from the Putin regime will worsen. If there is not much hope for a democratic uprising, what is the point? Zelensky is already facing criticism from Ukrainians who believe he is making a mistake by offering neutrality while staying away from Europe and NATO. His critics say neutrality means vulnerability and that people have seen that no Russian promise can be trusted – so any agreement signed by Putin must be guaranteed by the countries that are currently arming Ukraine. Their support, of course, may depend on the type of agreement Zelensky intends to reach. Just a few weeks ago, Zelensky seemed doomed, and Johnson offered to help him form a “government in exile” outside Kyiv. His decision to stay and fight gave him the right to agree to peace on his own terms. There may be no shortage of views in London on what kind of deal Ukraine should lead to if given the chance, but the decision, if it comes, will be solely for Zelensky.