So the industry that brought the world the Marlboro Man, Joe Camel and slogans like “Reach for a Lucky Instead of a Sweet” has latched onto the selfie generation’s screens in a highly adaptive way that skirts the advertising rules of old.

“What they are doing is a really effective way to get around existing laws to restrict advertising to young people,” said Robert V. Kozinets, a public relations professor at the University of Southern California, who led an international team of researchers examining the tobacco industry’s use of social media.

“The most surprising thing to me was the level of sophistication of these different global networks. You get incredible campaigns, the likes of which I’ve never seen before.”

International public health organizations are pushing back against tobacco companies around the world. Earlier this month, Bloomberg Philanthropies chose three international research centers to lead a new $20 million global tobacco watchdog group called Stop (Stopping Tobacco Organizations and Products), with partners in the United Kingdom, Thailand and France, that will partly focus on social marketing.

Dr. Kozinets’s work, paid for by the Campaign for Tobacco-Free Kids, an advocacy group, analyzed social media in 10 countries by looking for hashtags that connect to tobacco cigarette brands.