Weeks after the “100 percent preventable” derailment in East Palestine, Ohio, Secretary of Transportation Pete Buttigieg is pledging to finally get tough on a railroad industry that’s been resolute in fighting safety regulations. But environmental groups say Buttigieg’s department is still delaying action to block one of the railroads’ most reckless proposals to date: allowing so-called bomb trains to carry highly explosive liquefied natural gas (LNG) through populated areas.

Some twenty-five million Americans live in the one-mile evacuation zone of trains carrying crude oil, according to one estimate. Supercooled and highly compressed, LNG could prove an even bigger danger, and federal policy has long prohibited its transportation by rail. According to the law firm Earthjustice, the accidental breach of just one train tank car carrying the gas could trigger an explosion big enough to destroy a city, while twenty-two tank cars’ worth contains the energy equivalent of the nuclear bomb that destroyed Hiroshima.

A 2020 rule from Donald Trump’s Transportation Department reversed course and, for the first time, authorized the future train transport of LNG. Later that year, five environmental groups represented by Earthjustice, sixteen state attorneys general, and the Puyallup tribe of western Washington all filed legal challenges to the new rule, hoping to bar the dangerous practice before it began.