Off war-battered Yemen’s western coast lies a rapidly deteriorating storage vessel that could at any moment become an oil spill of catastrophic proportions. Experts say it’s not too late to avert disaster, but an eleventh-hour decision by the outgoing Donald Trump administration to blacklist the militants who control the tanker has raised the stakes.  

Last week, US Secretary of State Mike Pompeo announced he would designate the Houthi movement in Yemen as a “foreign terrorist organization” in what was seen as a final push to isolate Iran, the rebels’ regional backer. The label, which makes it illegal to provide material support or resources to the Houthis, drew an immediate backlash from the United Nations, humanitarian organizations and former US national security officials. 

The designation is likely to produce a chilling effect, with banks and commercial suppliers deciding it’s not worth the risk to do business in Yemen. Relief agencies that need the permission of Houthi-run government agencies to deliver aid fear the designation will put their staff at risk of US prosecution. 

The move could also complicate negotiations over the FSO Safer, a 45-year-old, single-hull storage tanker on the verge of leaking 1.14 million barrels of light crude oil into the Red Sea — about four times the amount released in Alaska’s Exxon Valdez spill in 1989.