Donald Trump has been tweeting again. A day after warning Russia to “get ready” for US missiles in Syria, Mr Trump seemingly sought to backtrack on his aggressive stance. “Never said when an attack on Syria would take place,” he tweeted. “Could be very soon or not so soon at all! In any event, the United States, under my Administration, has done a great job of ridding the region of ISIS. Where is our ‘Thank you America?’” The president’s apparent threat of military action on Twitter on Wednesday triggered deep unease among foreign policy specialists. Daniel Fried, a former ambassador who co-ordinated sanctions policy for the US government during the Obama administration, said Mr Trump’s tweets had put the US “in [the] same chest-thumping rhetorical space with Putin”. “Never thought we’d go full Khrushchev-table pounding, but here we are and it could hurt us,” said Mr Fried, referring to Mr Khrushchev’s 1960 shoe-banging protest at the UN.