Decaying oil tanker could trigger an environmental and humanitarian disaster. The FSO Safer is marooned off the coast of Yemen in the Red Sea, close to one of the world's biggest shipping lanes. A massive oil spill or explosion from it could disrupt global trade for months and lead to an environmental and humanitarian catastrophe. It's loaded with hundreds of tons of crude oil, its hull is rusting and it hasn't moved in years. So why isn't anybody doing anything about it? Nominally the Safer is the property of the Saudi-backed Yemeni government. Right now though, both it and its multi-million dollar cargo are controlled by the Houthi rebels in Yemen. UN officials say the Houthis have broken an agreement to allow an inspection of the vessel. The Saudis accuse them of holding the world to ransom over the potential disaster. The Houthis disagree. Ed Butler speaks to Ghiwa Naket, the executive director of Greenpeace for the Middle East and North Africa, to Ben Huynh a researcher at Stanford University, to Hussain Albukhaiti a Yemeni journalist with close links to the Houthi leadership and to Peter Salisbury, senior analyst for Yemen at the International Crisis Group.