Before he left Washington last week for the Nato summit, his UK visit and talks with Vladimir Putin, Donald Trump raised eyebrows by suggesting that the meeting in Helsinki on Monday might be the easiest one of the three. In retrospect, it is clear that this was not an off-the-cuff comment. It was his plan all along. First rough up Nato in order to damage transatlantic commitments, then stir things up in Britain in order to damage the EU, and, finally, play the cooperative statesman in his talks with the Russian president. Or, to put it another way: bully, bully and cringe.

The European visit and its outcomes have offered a chilling illustration of Mr Trump’s worldview. His strategy decries the values that endured in western policy since the defeat of Hitler. It is a conscious break with the postwar network of alliances and aspiration for universal standards. It is a return to the era in which big powers have self-interests not allies, little countries do not matter, and international standards are subordinate to military might. Because Russia is a significant military power, Mr Trump has brought it in from the cold. It is not just the cold war that is over. The post-1945 order of international values and ethics may be ending too.

Mr Trump went into the talks with Mr Putin offering bland banalities that signalled his readiness to resume business with Moscow: there were “a lot of good things to talk about”, the two sides had “great opportunities together”, it would be an “extraordinary relationship” and the world wanted “to see us get along”. Beside him, Mr Putin put on his stone face, saying little, giving nothing away. Five hours later, after two sets of talks, the leaders re-emerged. This time Mr Putin was garrulous. The talks had been successful and useful. Relations had moved to a different phase. There were no objective reasons why Russia and the United States could not cooperate strategically on military, anti-terror, economic and ecological issues. It was all smiles. Mr Putin even gave Mr Trump a football, to mark the end of Russia’s successful hosting of the World Cup.

As well he might, because the US president gave the Russian leader a far bigger present than a football. Mr Trump used the meeting to smooth Russia’s almost unconditional re-entry into his version of the international order. If the accounts that the leaders produced at their press conference on Monday evening are reliable, the issues that have made relations with Russia so difficult for so long – Ukraine, interference in elections, cyber disruptions and the Salisbury novichok attack – counted for very little in their talks. In his overeagerness, Mr Trump essentially gave Mr Putin a free pass.

Mr Putin was always likely to be the big winner from the Helsinki meeting. The mere fact that it took place was a victory for the Kremlin. But Mr Trump made it clear in Helsinki that he regards bygones as bygones. He is prepared to reset the dial. Mr Trump barely seems to have made an issue of Moscow’s unilateralism against Ukraine, so much so that Mr Putin was emboldened to suggest at the press conference that Washington was not putting enough pressure on Kiev to give in to Russian demands. The practical impact of the two men’s discussions on Syria and the Middle East remains unclear, but there was no suggestion that Mr Trump intends to take any kind of a stand here either. Russian interference in US elections – which has recently led to 12 Russians being charged – remains a very awkward obstacle. But not because of Mr Trump, who manifestly does not treat the issue seriously. Mr Putin returns to Moscow under less pressure than ever on all the difficult issues.

If Mr Putin is the big winner, Theresa May is one of the losers. The Salisbury novichok attack counted for nothing in Helsinki. In the Commons on Monday Mrs May talked about Nato to MPs as though nothing has changed. Britain and the US were on the same side on burden-sharing. Mr Trump’s approaches at Nato and in Britain had been constructive. This is nonsense. Mrs May talks as if the alliance is unchanged when in fact everything is changing. If she is to avoid Britain and her government becoming collateral damage in Mr Trump’s dangerous demolition of the global order, she will need to wake up very fast.