David Cameron was quite right to drop in on Donald Trump

Editorial: The former president and his supporters in Congress need to hear the message that the support for Ukraine is not only just, but also in America’s interest

Cameron criticised Trump when both men were heads of state but now is a good time to breach protocols (AFP)

The Foreign Office insisted that “it is standard practice for ministers to meet opposition candidates as part of their routine international engagement”. This is the opposite of the truth, which is that the convention is for ministers to avoid engagement with non-government politicians during election periods abroad to avoid giving the impression of interfering in another country’s politics.

But the convention is only a guideline, and David Cameron was quite right to adapt it to the needs of the hour. No one would have interpreted the foreign secretary’s visit to Donald Trump at his home in Mar-a-Lago, Florida, as a political endorsement of Mr Trump, the Republican presidential candidate-presumptive.

After all, one of the reasons for wondering about the wisdom of the stopover is that Lord Cameron has said some pretty rude things about Mr Trump in the past. When Mr Trump was president, David Cameron as prime minister called his “Muslim ban” travel policy “divisive, stupid and wrong”.

Mr Trump might recall, too, that they were on opposite sides of the European Union referendum question. Mr Trump had no compunction about interfering in British politics by backing Brexit, but equally, prime minister Cameron had more or less invited such interference by recruiting Barack Obama as a cheerleader for the other side.

Yet it was worth taking the risk that Mr Trump might end up being less persuaded by Lord Cameron’s argument than he was to begin with, because of the importance of that argument. The foreign secretary is engaged in a noble mission, which is to rally international support for Ukraine in its just war against Vladimir Putin’s aggression.

We do not know what arguments Lord Cameron deployed with Mr Trump, but the simplest one would be the truth, which is that defeat for Ukraine would be a disaster and a humiliation for democracies across the world.

Mr Trump has said some careless things about Europe looking to its own defence, but if he becomes president again, he will inherit a war in which the United States has for more than two years been committed on the side of freedom and self-determination. The withdrawal of American support would look like weakness, and however much Mr Trump may have admired Mr Putin’s ruthlessness in the past, he cannot want the Russian leader to be seen to have prevailed over him.

If Lord Cameron got this message across, he might have overcome Mr Trump’s hostility to the messenger.

The foreign secretary will have taken a similar message to Washington on Tuesday, when he met Antony Blinken, US secretary of state, and congressional leaders. Not that Mr Blinken needs any persuading of the need to stay the course in Ukraine, but he needs support in trying to overcome Republican opposition to funding for the war. Again, given how much the current Republican Party is in thrall to Mr Trump, this reinforces the rationale for the Mar-a-Lago leg of Lord Cameron’s trip.

The foreign secretary’s case is simple: that American pride and self-interest happen to be engaged on the side of doing what is right in Ukraine, namely defending the freedom of the Ukrainian people against Mr Putin’s aggression. Travelling straight from a Nato summit in Brussels, Lord Cameron can point out that Europe is increasingly willing to bear a greater share of this burden.

Nor is Ukraine like Afghanistan, where a US-led force was propping up the government and the case for staying was marginal. The Ukrainians are overwhelmingly committed to fighting their own war; they simply ask for the resources with which to fight it. Mr Trump was able to delay the scuttle from Afghanistan until Joe Biden took over: he cannot distance himself from pulling the plug on Ukraine if he returns to the White House in January. He needs to be prepared to stick with Ukraine for a full four years.

If Lord Cameron succeeded in getting any part of that message over to the former president, and to his supporters in Congress, his breach of protocol will have been worthwhile.