In this dangerous age, Britain needs to exert soft power as well as the hard stuff

Shortly before he flew to Washington, Sir Keir Starmer turned up in the Commons, put on his sombre voice and declared: "Everything has changed."

- Andrew Rawnsley

One of the more startling transformations has been to Sir Keir himself. The Labour leader came to office thinking, as did most of those who voted for him, that he was going to be a domestically orientated prime minister with primary ambitions to improve living standards, build lots of homes and rejuvenate public services. That's what "change", his one-word election slogan, was supposed to be about. When he originally selected his overriding "five missions", the defence of the realm didn't make the cut.

His central definition today is as a geopolitically focused prime minister who is promising to spend more on guns, missiles and warplanes and less on international aid. More British bullets will be purchased at the expense of succour to the impoverished and desperate of the world. This shift gives a flintier profile to his leadership, but not in a way that either supporters or opponents anticipated during last summer's election. Most Labour people don't quarrel with the argument that Britain has to put up its guard, but a lot of them, including queasy members of the Starmer cabinet, are wriggling uncomfortably about taking the hatchet to the international development budget. In the days since the decision was announced, they have taken to wondering what manner of Labour government is this?

The short explanation for this transmogrification is Donald J Trump. The upheaval in the international order unleashed by the US president has shattered decades-old assumptions about the western alliance. This has had a more profound impact on Sir Keir than any other event. A prime minister who used to earn his living as a human rights lawyer has had a crash course in realpolitik from the nakedly transactional practitioner of great power games who resides on Pennsylvania Avenue.