Federal health officials on Thursday delayed a high-stakes decision on whether to permit the bestselling vaping brand Juul to stay on the market, while banning the sale of thousands of other electronic cigarettes in the US.

The Food and Drug Administration (FDA) said it rejected applications for nearly 950,000 e-cigarettes and related products, mainly due to their potential appeal to underage teens.

Some of the products are currently being sold while many others were only proposed by manufacturers. But the agency did not rule on Juul, the most popular brand with adult smokers and many teens.

Parents, politicians and anti-tobacco advocates have pressured the FDA for years to ban Juul’s high-nicotine devices, which many blame for the recent spike in underage vaping. But the agency said it would need more time to rule on that company’s products.

It also noted that 80% of teens and children who vape use flavored products.

Thursday’s action is part of a sweeping review by the FDA to bring scientific scrutiny to the multibillion-dollar vaping industry after years of regulatory delays. The agency has yet to authorize any vaping product as a less harmful option for smokers.

The FDA faced a court deadline on Thursday to issue decisions on marketing applications from Juul and hundreds of other companies. The date was set by a federal judge after anti-tobacco groups successfully sued the FDA to speed up its review.

To stay on the market, companies must show that their e-cigarettes benefit public health. In practice, that means proving that adult smokers who use the products are likely to quit or reduce their smoking, while teens are unlikely to get hooked on them.

FDA regulators previously said they would prioritize Juul and a handful of other key players, but none were included in the agency’s announcement.