Tobacco companies Philip Morris and Altria are discussing a merger that would reunite the Marlboro maker with the parent company that sold it off a decade ago. The two companies confirmed they were discussing an all-stock merger but have disclaimed that there was no guarantee a deal would be reached.

According to a BBC News report, analysts said the rationale behind the deal was to face up to declining cigarette sales. Altria has diversified in recent years beyond traditional tobacco, taking stakes in wine, beer and cannabis companies, as well as Juul.

Rival British American Tobacco (BAT) finalized its takeover of Reynolds American Incorporated in 2017, creating the world’s largest tobacco company. That merger too was driven by falling sales and the rise of e-cigarettes and vapes.

According to the World Health Organization (WHO) about 1.1 billion people smoked tobacco in 2015. WHO estimates smoking leads to 6 million deaths a year. Thanks to public health initiatives, taxes and other regulations smoking is on the decline in many parts of the world but WHO points out that smoking is on the rise in the eastern Mediterranean region and across much of Africa.