The F.D.A. said it would provide more detail on how to restrict access at a later date. But Dr. Gottlieb said putting the vaping products under counters would not be sufficient. “What we are envisioning is a separate room or a walled-off area,” he said. “It needs to be a complete separate structure. A curtain won’t cut it.”

Industry lawyers challenged the commissioner’s authority to impose such requirements. “The Tobacco Control Act is clear that the F.D.A. can’t discriminate against one type of retail outlet and that’s what they’re trying to do here,” said Doug Kantor, counsel to the National Association of Convenience Stores. “There is a very good chance this will end up in litigation and lawyers are looking at that right now.”

Critics said that exempting menthol and mint e-cigarettes from the restriction was misguided, because of the large number of youth vapers who buy them.

But Mr. Chowdhury considered Juul’s pre-emptive move to limit visible flavors to mint, menthol and tobacco shrewd. If indeed a ban on menthol cigarettes is enacted, he said, “Juul is in a good position to offer an alternative product for smokers who are used to their menthol flavor. Because Juul has market dominance, they stand to benefit from an ultimate ban.”

But a prohibition against menthol cigarettes would have to clear the usual federal regulatory hurdles, a process that could take at least two years. If successful, the menthol ban could make a significant dent in cigarette sales. Menthol cigarettes account for about 35 percent of cigarette sales in the United States.

[Answers to common questions about the health effects of e-cigarettes and teenage vaping]

Murray Garnick, the general counsel for Altria Group, which sells vaping products like MarkTen Elite and Apex through its Nu Mark subsidiary, said in an email that the tobacco giant welcomed the F.D.A.’s new e-cigarette policies.

But, he predicted a lengthy debate over the proposed prohibition on menthol cigarettes: “We continue to believe that a total ban on menthol cigarettes or flavored cigars would be an extreme measure not supported by the science and evidence.”