Menthol cigarettes account for a third of the industry's overall market share in the United States
The defense ministry initially said background radiation had remained normal after the incident on Thursday, but city authorities in Severodvinsk in northern Russia said there had been a brief spike in radiation levels.
Greenpeace has said radiation levels rose by 20 times.
Russia’s state weather agency, Rosgidromet, said on Tuesday that it believed radiation levels had risen by four to 16 times.