The alert said that there is ‘no operational threat tied to a specific location’ The latest headlines from our reporters across the US sent straight to your inbox each weekday Your briefing on the latest headlines from across the US Your briefing on the latest headlines from across the US Email * SIGN UP I would like to be emailed about offers, events and updates from The Independent. Read our Privacy notice Iran has potentially sent out “an operational trigger” to activate “sleeper assets”