Fresh US strikes triggered air defences in Tehran on Wednesday after President Donald Trump warned he was "not finished" with a war with Iran that has already cost his nation $37.5 billion.

As the US enters the ninth night of Iran strikes, oil has climbed to the highest level in more than a month to over US$91 a barrel.

The United States renewed its strikes on Iran, where an air raid alert was triggered Wednesday in Tehran, after US President Donald Trump warned he was “not finished” with the…