A threat from Iran prompted moves by the US Secret Service to boost protection around Donald Trump before Saturday’s attempted assassination of the former president, which appears unrelated to the original threat, according to two US officials. Upon learning of the threat, the Biden administration reached out to senior officials at the Secret Service to make them aware, the officials said, adding it was shared with the lead agent on Trump’s protection detail and the Trump campaign. That prompted the agency to surge resources and assets to protect Trump. The officials spoke on the condition of …