Friedrich Merz , the German chancellor, already embroiled in a row with Donald Trump over the Iran war, has said he would not advise his children to study or work in the US in the current climate. Speaking to a conference of young Catholics in Würzburg, the conservative leader, viewed by many as a transatlanticist, said he no longer saw the US as the land of opportunity. “I am a great admirer of America. At the moment my admiration is not growing,” he said during a podium discussion, citing the quickly changing “social climate” in the deeply polarised country.…