The Food and Drug Administration (FDA), which regulates medical products in the United States, has approved the sale of an electronic cigarette for the first time.
It has cleared three products from RJ Reynolds, under the brand Vuse.
The FDA has decided that the benefit for adults trying to quit smoking outweighs the risk of teens getting hooked.
The authorized products are flavored with tobacco, unlike the sweet flavors appreciated by the youngestes.
Electronic cigarettes have been sold widely in the United States over the past decade, but their adoption by adolescents has raised concerns.
Manufacturers have been waiting for official clearance for over a year, as the FDA examines the potential benefits and harms to public health.
The FDA, which has received the power to regulate new tobacco products over a decade ago, conducted a study on electronic cigarettes to decide which ones can continue to be sold.
A decision on market leader Juul is still pending.
A study released last month by the FDA and the Centers for Disease Control (CDC) estimated that more than two million school students have used e-cigarettes this year, of which 80% use flavored products.
Tuesday's FDA ruling applies to the Vuse Solo ENDS electronic cigarette and tobacco thatAccompany it - flavored pods.
Explaining the reasoning of the FDA, Mitch Zeller, its director of tobacco products said: "Manufacturer's data shows that its tobacco flavored products could benefit addicted adult smokers who switch to these products. - either completely or with a significant reduction in cigarette consumption - by reducing their exposure to harmful chemicals.
He also warned that the authorization could be withdrawn if there were any signs of significant use of the product by people who have not used tobacco before, including young people.
The FDA said young people were "less likely to start using tobacco. ENDS tobacco-flavored products, then switch to higher-risk products, such as burnt cigarettes.
"Data also suggests that most youth and young adults who use ENDS asncent by flavors such as fruit, candy or mint, not tobacco flavors. "
RJ Reynolds must also comply with restrictions on digital and television products under the decision.
But the FDA has rejected the authorization of 10 other Vuse Solo flavored products, without specifying which ones, and said they should be taken off the market if they are on sale.
The American lung The association, which makes campagne against smoking, expressed disappointment with the FDA's decision.
"The American Lung Association is appalled that the FDA will allow three products to continue on the market in the United States, including products that contain nearly 5% nicotine. The damage that these products cause young people to show that they do not meet the public health standards of the Tobacco Control Act. "
RJ Reynolds, who is part of British American Tobacco, said that the ruling showed its vaping products to be suitable "for the protection of public health".