Donald Trump has sold out Ukraine. He makes Chamberlain look like a man of iron principle | Simon Tisdall

Historical comparisons are always inexact. No one conflict precisely mirrors another. Yet Donald Trump’s shameless appeasement of Vladimir Putin carries more than a noxious whiff of Neville Chamberlain’s failed attempt in Munich in 1938 to head off war with Nazi Germany. To be fair to the former UK prime minister – and history largely hasn’t been – his peacemaking efforts had the enthusiastic backing of most people in Britain and France who, like him, were desperate to avoid a repeat of the horrors of the first world war. Trump enjoys no equivalent public support for his treachery. Nor does he face the prospect of a US war with Russia. His betrayal of Ukraine is cynically self-interested, globally dangerous and utterly contemptible.

US-Russian talks on agreeing the shoddy terms of a precedent-setting American sell-out of Ukraine are at an advanced stage, after meetings in St Petersburg this week. Trump has zigzagged over the war ever since returning to office. Now, panicked by record-low poll ratings, he seems determined to scapegoat Ukraine and force its de facto capitulation. Recent steps – his shocking decision to fund Putin’s war machine by buying Russian diesel, his waiving of tougher sanctions, his mysterious, lethal interruptions in US satellite and intelligence sharing with Kyiv, and his renewed attempt to oust Ukraine’s president, Volodymyr Zelenskyy – mark Trump out as the skulking Judas, the craven Brutus of the modern age. He makes Chamberlain look like a man of iron principle. All that’s lacking is an umbrella.

Why does Trump act this way? Partly, it’s personal. He doesn’t like Zelenskyy and it’s obvious why. Ukraine’s leader is everything he is not: courageous, principled, morally unimpeachable, hard-working and politically savvy. Partly, it’s money and power. Trump has set his shrivelled, grasping heart on normalising relations with Putin’s repressive rogue regime, opening the way for lucrative deals on energy, raw materials, and control of the Arctic and outer space. He likes the idea of a world dominated by three all-powerful blocs and authoritarian leaders: himself, Putin and China’s Xi Jinping. And partly it’s the unexplained, sinister hold Putin appears to exercise over this former society playboy, New York real-estate developer and serial bankrupt.

Whatever Trump’s motivations, the short-term consequences of his betrayal are potentially fatal for Ukraine’s bid to repel the Russian invaders and survive as a sovereign democratic state. For much of this year, Ukraine has been winning, or at least holding its own, in the contested lands of the Donbas and along the Black Sea littoral. More than that, by using homemade missiles and drones, it has taken the fight to Russia’s industrial heartlands and oil refineries, significantly undermining Putin’s ability to fund his war. Zelenskyy has also been winning the battle for international opinion, particularly in Europe, which itself is under escalating Russian hybrid attack. Amid Trump’s egregious backsliding, European nations have taken the lead in supporting Kyiv militarily, financially and diplomatically.

It’s hard not to wonder whether there’s a connection between Trump’s sudden, divisive, decisive lurch towards unabashed support for Putin and the fact that Russia, suffering unsustainable battlefield casualties, severe economic damage and deepening international isolation, is at increased risk of regime-toppling humiliation. Whatever the truth, Trump’s Putin bailout – his duplicitous Russia rescue act – could turn the tide.

Trump’s perfidy is the shame of the world, and it is the world – and not only Ukraine – that will pay the price over the longer term. This calculated attempt to force Kyiv’s submission imperils everyone. Ukraine, if it is allowed to fall, will haunt Europe and the wider geopolitical biosphere for decades, as was the case with Czechoslovakia after 1938. Trump’s Molotov-Ribbentrop-style pact with a warmongering dictator, an indicted war criminal, a smirking, bigoted mass murderer, may fatally compromise the western alliance and spell the end of Nato as an effective defence against eastern totalitarianism. Who among the democratic governments of western Europe, in the Elysée, in the German and Polish chancelleries, in Brussels or in Downing Street, can now trust a word that comes out of Washington? Its bond is broken, its honour in shreds.

Trump’s betrayal follows a pattern of lesser treacheries: arbitrary tariff wars waged against trading partners, the traducing of loyal allies, threats against Canada and Greenland, abandonment of a two-state solution in Palestine and most recently, his disastrous war against Iran – the real reason why US midterm voters, facing inflated fuel prices, are turning against him and his Republicans. But his Russian folly may be the most egregious and consequential. As MI5 has warned, Britain and Europe are under daily attack from Russia, its spy networks, saboteurs, cyber warriors and paid agents. Reports this week suggest it is menacing western space satellites, too. Don’t look to turncoat Trump for help. He’s on the other side.

Trump’s Munich moment is a disaster in the making for Europe’s security and defence. A Putin victory, accepted and facilitated by the US, would fatefully damage respect for international law and sovereign borders. Untold numbers of war crimes and crimes against humanity would go uninvestigated and unpunished in a partitioned, fractured Ukraine. China and others might soon follow the precedent established by successful Russian aggression. For all these reasons, Britain and its European allies can no longer afford to hold back. Indignant speeches at the UN, off-the-record murmurings and carefully calibrated verbal slaps on the wrist will not suffice, if they ever did. Andy Burnham, France’s Emmanuel Macron, Germany’s Friedrich Merz and Canada’s Mark Carney must lead the way in confronting Trump head-on, even at the cost of a definitive break with Washington.

Tell Trump publicly to knock it off. Take concrete steps to punish him for rewarding Putin and prove that the democracies of the world will not be bullied and sold out. Tell him if he really wants to be remembered as the US president who shattered the western alliance and ensured the triumph of authoritarianism, then keep on licking Putin’s boots – but he will be on his own. The UK, EU and Nato member states, Japan, South Korea and other like-minded countries, are far from powerless, economically, militarily and in numerous other ways. And despite what polls may suggest, healthy majorities of their citizens reject the hateful far-right lies and sick populist myths on which Trump and his pitiful emulators feed.

The US ultimately leads the west by consent, not by right. Consent can be withdrawn. Burnham could start by ordering the closure of US military bases in Britain, offensive symbols of a hostile occupying power. At all costs, Trump’s treachery must not stand.