The leader of e-cigarette startup Juul Labs Inc. abruptly exited and two tobacco giants abandoned their blockbuster merger, as the regulatory pressure to combat underage vaping swept through the industry.

Juul, which is the target of several federal investigations, said Chief Executive Kevin Burns was replaced Wednesday by an executive at tobacco giant Altria Group Inc., MO -0.42% which owns a 35% stake in the e-cigarette maker.

The San Francisco company, which faces a potentially crippling U.S. ban on most of its products, cited the need to focus on regulatory matters for the leadership shift. Juul said it wouldn’t lobby against the Trump administration’s proposed ban on most flavored e-cigarettes and would suspend all its broadcast, print and digital advertising in the U.S.

Altria and Philip Morris International Inc. PM 5.20% on Wednesday ended their talks for a potential merger of the two Marlboro makers, a deal that would have created a global player worth nearly $200 billion. The talks were spurred in part by the threat Juul posed to their traditional businesses as some smokers switched away from cigarettes.