Washington is fully prepared for an armed conflict with Iran -- says the US defence department. The Pentagon chief Leon Panetta says there's still room for dialogue but sufficient military forces are in the Persian Gulf in case Tehran decides to block a vital oil route there. This comes after Iran said it would close the Strait of Hormuz only if the country's security -- and the security of its nuclear facilities -- is threatened. Tehran is backed by Russia which says military action would bring disastrous results. Iran agreed to resume six-party talks over its atomic programme. But there are fears the country is already under attack, after the latest murder of one of its nuclear scientists, which Tehran blames on Israel. Former CIA officer Philip Giraldi says a military confrontation in the Gulf could lead to a new world war.