The war on things that happen to look like smoking has reached 33,000 feet. The Department of Transportation announced on Wednesday that it would ban the use of e-cigarettes on commercial airplanes. (Many airlines had already taken the action, before the government decided to step in.)

It’s not entirely obvious why the DOT took this step; unlike actual cigarettes, e-cigs contain no tobacco. They emit vapor, rather than carcinogenic second-hand smoke. And so, the DOT claims that it is merely clarifying things: “The Department took a practical approach to eliminate any confusion between tobacco cigarettes and e-cigarettes by applying the same restrictions to both,” said DOT chief Anthony Foxx in a statement. In other words, e-cigarettes look too much like actual cigarettes. It’s very confusing!