Former foreign minister Alexander Downer warns US President Donald Trump a "half-hearted" war with Iran would hand the regime a victory and weaken American power. “Don’t go to war with somebody unless you’re going to be ruthless and prosecute that war until you win,” Mr Downer told News24 host Chris Kenny. “Being half-hearted about it, he will get a half-hearted result that will be seen as a sa victory for the IRGC and a weakening of American power. “In the end he has to seize control of the Strait of Hormuz, then blockading the Iranian port will ensure that the IRGC have no significant source of revenue.”