W hat began as a spat between Friedrich Merz and Donald Trump over the Iran war is rapidly turning into a historic rupture between Germany and the US. Its significance is hard to overstate. In Germany, the transatlantic falling-out adds to the domestic woes of a coalition government in crisis, overshadowing the first anniversary of Merz’s becoming chancellor tomorrow. More importantly, it proves the futility of Merz’s attempt to be Europe’s Trump-whisperer and puts Nato’s credibility into question. But the dispute also boosts the ambition that Germany’s conservative leader set out on the night of his party’s election victory: to make Europe more independent from the US security umbrella. This rupture started with the chancellor’s remarks last week about the stalling talks between the US and Iran.…