The threat to ships carrying oil in the Middle East is at its worst since the Iran war started, experts have said, after a spate of attacks on another key route in the region. The warning comes after a number of attacks on vessels in the Red Sea, an alternative waterway that some tankers had been using since Iran blocked the Strait of Hormuz. Many ships have been "going dark" when crossing the strait, meaning they turn off their transponder to avoid detection. For much of the war, some ships carrying oil from Saudi Arabia had instead passed through an alternative shipping lane in the Red Sea, between the kingdom and northeast Africa. But a recent spate of attacks by Yemen's Houthi fighters on Saudi tankers using the alternative waterway has further heightened the risks.