Washington’s Middle East allies are bracing for what they fear could be “catastrophic” consequences if the United States moves militarily against Iran – a possibility US President Donald Trump again dangled this week by promising Iranian protesters that “help is on its way”. Despite Trump’s vow of support, analysts warn that even a sustained US air campaign would be unlikely to unseat Ayatollah Ali Khamenei’s regime. The US president’s rhetoric has followed a now-familiar arc, echoing his...