It’s hard being a teen. Between bodily changes, peer pressure, various identity crises, and that nagging tension between knowing everything and nothing at all, it’s surprising that anyone makes it out of adolescence at all.

It follows, then, that teens might try to massage this anxiety with substances, the way many of their adult counterparts do. (Also, teens just want to have fun, man.) Unsurprisingly, the FDA is most definitely opposed to this, and it’s particularly concerned with vaping. It appears to be hellbent on two things: preventing vape products from reaching teen consumers, and finding out why, exactly, teens love to vape so much.

These goals were laid out in a memo published Tuesday. FDA Commissioner Scott Gottlieb announced that the agency had sent letters to 40 retailers nationwide—the full list of which can be found here—warning them that they had violated laws against selling e-cigarettes to minors, which it discovered by way of “a large-scale, undercover nationwide blitz.” The letter noted that retailers may face “regulatory action” if they don’t address the violations, including financial penalties.

Besides making it clear it doesn’t entirely get this whole vaping thing—“We understand, by all accounts, many [young people] may be using products that closely resemble a USB flash drive”—the agency also detailed another intriguing strategy: hounding the manufacturers for their secrets directly.

From the announcement:

Today, the FDA also sent an official request for information directly to JUUL Labs, requiring the company to submit important documents to better understand the reportedly high rates of youth use and the particular youth appeal of these products. The information we’re requesting includes: documents related to product marketing; research on the health, toxicological, behavioral or physiologic effects of the products, including youth initiation and use; whether certain product design features, ingredients or specifications appeal to different age groups; and youth-related adverse events and consumer complaints associated with the products.

JUUL, for the uninitiated, is a popular e-cigarette company. Yet it doesn’t seem visibly bothered by the FDA’s focus, despite the fact that it was the only company specifically targeted in the “blitz.”

"JUUL Labs agrees with the FDA that illegal sales of our product to minors are unacceptable,” a spokesperson wrote in an email to Motherboard. “We already have in place programs to prevent and, if necessary, identify and act upon these violations at retail and online marketplaces, and we will announce additional measures in the coming days.”

In a press release sent to Motherboard, KanydPens, which is also mentioned in the FDA's announcement, said that the FDA Commissioner improperly included it in a category with JUUL and other e-cigarette products that contain nicotine. "KandyPens does not, and never has, made any pre-filled liquid nicotine pods," the company said. "Rather, all KandyPens’ products are sold empty – without any liquid, e-juice, or concentrate – and are for aromatherapy purposes only. KandyPens deliberately designed its products to enable each individual user to decide what to insert into the pods and KandyPens’ products are not intended for use solely with nicotine."

Andrew Gregson, Director of Corporate and Legal Affairs at Fontem Ventures, the company that owns Blu and that is also mentioned in the FDA's announcement, said that its products are made for adult smokers. "As such, we fully support and advocate for legislation prohibiting sales of vaping products to minors, and also respect the recent FDA enforcement action against retailers selling e-vapor products to minors detailed in today’s FDA statement," Gregson said.

The crackdown on underage vaping is reminiscent of the FDA’s wars on other products that seemed to attract teens, including Four Loko and certain flavors of tobacco. But while those crusades ended with outright bans or changes in ingredients, it’s unclear what the endgame is when it comes to vaping—after all, it’s still perfectly legal for adults. For now, America’s teens will likely continue to fool their teachers and parents, who keep wondering why kids these days keep carrying around USB drives.

Update: This article has been updated with comments from Fontem Ventures and KandyPens.