On Wednesday, U.S. Food and Drug Administration (FDA) Commissioner Dr. Scott Gottlieb released a statement announcing three significant developments related to the agency’s regulation of e-cigarettes.

The statement indicates that the FDA has sent more than 1,100 warning letters to businesses for the illegal sale of e-cigarettes to minors, as well as 131 civil money penalties to stores that continued to violate the restrictions on sales to minors. These actions constitute the largest enforcement action in the agency’s history.

Additionally, the Commissioner said that the FDA was “seriously considering” pulling flavored e-cigarettes from the market, calling their rising use among underage youths an “epidemic.” To that end, the agency announced it had sent letters on Wednesday to Juul and other top e-cigarette manufacturers, asking them to respond within 60 days with plans for reducing teen use or risk having their products pulled from the market. The Commissioner also said the FDA would be conducting “boots on the ground inspections” of the marketing and sales practices of e-cigarette manufacturers.

The agency is also revisiting the compliance policy that was announced last summer to extend the application compliance periods for certain deemed products, including e-cigarettes that were on the market as of Aug. 8, 2016. Under the current policy, the compliance date for filing applications for such products was extended to Aug. 8, 2022. The FDA says they still consider electronic nicotine delivery system (ENDS) products as potentially useful tools to help adults stop smoking, but the “accelerating use among youth” is causing the agency to “actively consider” the stricter premarket review process earlier than originally intended.