The FDA has ordered three tobacco companies to stop claiming their cigarettes are “additive-free” or “natural.” The agency said those claims could mislead smokers into thinking those cigarettes are safer than others.

Letters were sent to ITG Brands LLC (which sells Winston cigarettes), Santa Fe Natural Tobacco Company Inc (American Spirit), and Sherman’s 1400 Broadway NYC Ltd (Nat Sherman).

The move marks the first time the FDA has taken this kind of step since it got expanded powers to regulate tobacco products in 2009. That included the authority to require that any claims suggesting a product is safer than regular cigarettes must be proven to be true.

The agency gave the companies 15 days to respond.