The battle against cigarettes in the U.S. has been raging for decades. Now, the U.S. has started another fight—this time, against e-cigarettes.

Vaping represents an "addictive" and "harmful" threat to young people—and they're booming in popularity, with more high school students smoking e-cigs than regular cigarettes, said U.S. Surgeon General Vivek Murthy, M.D., M.B.A., in a new report released Thursday.

“E-cigarettes went from being rare in 2010 to being the most common tobacco product used by our nation's youth,” Murthy said during a press conference. "This represents a staggering development in a relatively short period of time, and it threatens 50 years of hard-fought progress we have made curbing tobacco use and puts a new generation at risk for ...  addiction.”

Murthy's announcement comes on the heels of the FDA's ban on selling e-cigarettes to minors, announced in May, which added some teeth to government regulation of sales and product manufacturing in America.

The ban has also seen some support from the e-cig industry. "The electronic vapor industry is committed to keeping vaporizers out of the hands of underage consumers," V2, the largest independent e-cigarette and vaporizer company in the U.S., said in a statement released Thursday in response to the surgeon general report. "These devices are not and have never been intended for anyone under the age of 18. We support a ban on sales to underage users, and agree with commonsense decisions to establish a minimum purchase age for these products."

Because e-cigarettes are such a new phenomenon, the scientific research on vaping is still inconclusive and somewhat contradictory, and depends where it's coming from—American research on e-cigarettes has tended to be more negative, linking them closely with "analog" cigarettes, while British research has tended to regard vaping favorably compared to smoking. Public Health England declared in 2015 that e-cigs are 95% less harmful than tobacco cigs, and that they might even be able to help smokers quit smoking entirely.

But other research has suggested otherwise: One 2015 Harvard study published in Tobacco Control suggested that pyrazines, which are chemicals often added to e-cig "juice," may ultimately make it more difficult for vapers to quit. Another massive meta-study of e-cig users (some as young as 15), done at U.C. Berkeley and published January in the U.K. medical journal Lancet, suggested that former smokers who tried e-cigs were actually 28% less likely to quit smoking, contradicting the Public Health England report. "While there is no question that a puff on an e-cigarette is less dangerous than a puff on a conventional cigarette, the most dangerous thing about e-cigarettes is that they keep people smoking conventional cigarettes," coauthor Stanton A. Glantz, Ph.D., said. Then there's the case of a 48-year-old Brit, Dave Aspinall, who suffered injuries as bad as gunshot wounds after his e-cig exploded and nearly burned down his apartment.

So yeah, the research is still a little scattershot at this point.

Looking for a reason to quit cigarettes? Here are just a few we've covered:

— Smoking may reduce the number of Y chromosomes in a guy's cells.
— Smoking 10 cigs a day (what they call "light smoking" in Australia) can take 10 years off your life.

For more on the story, read the complete report at the U.S. surgeon general site, or read more coverage at USA Today.