Global oil prices have surged once again as tensions in the Middle East continue to escalate. Brent crude has climbed above $100 a barrel for the first time since May. While much of the focus has been on the strategic Strait of Hormuz, shipping through the Red Sea is also coming under growing threat after Yemen's Iran-backed Houthi rebels said they targeted two Saudi oil tankers. The escalation comes as Donald Trump said he was considering a "massive attack" on Iran, prompting Tehran to warn it would hold accountable any country supporting a US strike. Peter O'Brien reports.