South African wireless carrier MTN Group Ltd. has been sued in the U.S. for allegedly paying bribes to stop Taliban fighters blowing up its cellphone towers in Afghanistan. Families of almost 150 U.S. service members and civilians who were killed or wounded in attacks are accusing Johannesburg-based MTN of paying Taliban officials protection money so it didn’t have to invest in costly security for the transmission masts, according to a court document. Africa’s largest wireless carrier chose to be an “aggressive practitioner of protection payments,” according to the suit. It also alleged that MTN provided...