President Trump announced this week that he had held a ‘lengthy and highly productive’ phone call with Vladimir Putin, ending three years of diplomatic silence between the White House and the Kremlin. Their conversation, according to Trump, was an attempt to begin negotiations to end the war in Ukraine. But it had taken place without any prior consultation with the Ukrainian president, Volodymyr Zelensky.

We have been here before. In 1938, with the Munich Crisis, and in 1945, when Churchill and Roosevelt appeased Stalin over the fate of Poland. Both cases are instructive when it comes to the psychological traps that lie in store for any democratically elected government attempting to negotiate with a dictator.

The first thing that Trump and his team must keep in mind is that they are not playing on a level playing field. The US might appear to be the more powerful party, but it is Putin who holds the psychological advantage.

When Chamberlain began his negotiations with Hitler in 1938, he did so with the sincere intention of preventing bloodshed: as he was fond of saying, ‘In war there are no winners, but all are losers.’ He knew that his electorate did not want war either. In the words of one of his top diplomats, Robert Vansittart, British foreign policy had become hopelessly ‘tangled up with vote catching’.

There were also strong economic incentives to avoid war at all costs. The First World War had almost bankrupted Britain, and Chamberlain knew that a repeat would probably mean the end of the British Empire. As he said, there was no reason he should risk the bones of a single British grenadier over the fate of a far-off country like Poland or Czechoslovakia.

Trump faces a similar situation today. His government is spending billions of dollars supporting a war that the American people have little interest in, and which many actively oppose. There are strong moral arguments for bringing an end to the killing, even at the expense of Ukrainian sovereignty.

Hitler, like Putin, had none of these concerns. He had no interest in moral arguments, in sparing human life, or preserving his economy. He was not beholden to an electorate. He had no empire to lose, only one to gain. His only concern was the illusion of German greatness, and his own place in history as the leader of the thousand-year Reich. His deal with Chamberlain was merely a means to this end. After it was no longer useful, he immediately discarded it and went to war anyway.

The situation that confronted the West towards the end of the Second World War provides a different, but equally valuable lesson. In February 1945, when Churchill and Roosevelt met Stalin at Yalta to discuss the future of Poland, they came with an even weaker hand to play. Despite their combined economic power, they lacked the one thing that Stalin possessed – namely an army that was already in control of the ground.

Stalin made it clear from the start that he was unwilling to give up any of the land that his armies had conquered during the war. ‘For Russia it is not only a question of honour but also of security,’ he said. Putin regularly echoes these words today.

Stalin would go on to annex vast tracts of Polish land into the Soviet Union – the very same lands that now make up western Ukraine – and exercise control over the rest of Poland through the power of the Red Army. Virtually the only concession that the West was able to extract from him was a promise of free and fair elections in Poland at some unspecified time in the future.

During their negotiations, both Churchill and Roosevelt tried to cover up their unexpected powerlessness by resorting to wishful thinking. Each convinced himself that he had formed some kind of personal friendship with the dictator. Each chose to believe Stalin’s promises – despite everything they knew about his previous record.

During the course of the negotiations, Roosevelt told US radio audiences that they had nothing to fear from Stalin. ‘I believe that we are going to get along very well with him and the Russian people’, he announced that Christmas, ‘very well indeed.’

Churchill was, if anything, even more deluded. Stalin ‘meant well to the world and to Poland,’ he told his War Cabinet shortly after returning from Yalta. ‘Poor Neville Chamberlian believed he could trust Hitler. He was wrong. But I don’t think I’m wrong about Stalin.’

It did not take long for the scales to fall from their eyes. Within two years it was clear to all that Poland had not regained its freedom. Like every other nation in eastern Europe it became a vassal state controlled by a puppet government answerable only to Moscow. This is the same scenario that Putin envisages for Ukraine today.

When Hitler annexed the Sudetenland from Czechoslovakia in 1939, the West stood by in the hope that the sacrifice would lead to ‘peace in our time’. When Putin annexed Crimea in 2014, the West likewise did nothing. In both cases a brutal dictator was emboldened by what they perceived as western weakness, and went on to launch a much larger attack on the rest of the country concerned.

After the failures at Yalta, the West finally learned not to trust the word of European dictators. The age of appeasement was over: from 1947 onward they stopped trying to negotiate, and adopted instead a policy of containment.

This was basically the same policy that America adopted towards Putin after he invaded Ukraine three years ago. Its abandonment this week by has unnerved European diplomats and security specialists, who fear a return to the mistakes of the past.

Trump and his team believe they can defy the lessons of history and create a quick fix for this war. If they are to have any chance of success, they will have to play a better hand than Churchill and Roosevelt played in their negotiations with another Russian dictator 80 years ago.

America’s power has always lain not only in its military might, but in its vast economic wealth and its influence over world trade. In 1945, America accounted for 50 per cent of the world’s total GDP, and yet at Yalta Roosevelt failed to use his absolute grip on the world’s economy to pressurise the Soviets into being more accommodating. President Trump, though not in quite such an all-powerful position, will need to make much better use of America’s economic influence when dealing with Putin.

Any negotiations must be as clear-headed from the American side as they are likely to be for the Russians. This needs to be a conversation about territory only – how much to give away, and for what economic incentives.

Above all, there should be no question of signing away Ukrainian sovereignty. This is what the British and Americans did to Czechoslovakia and Poland in 1938 and 1945. It took 80 years for the West to finally be forgiven.