Two South African engineers working in Equatorial Guinea’s offshore oil fields were preparing to return home in February 2023 when they were arrested for cocaine trafficking and thrown in jail, where they remain. Both men, their families and their employer have declared their innocence. They were detained days after a South African court ordered the seizure of one of Equatorial Guinean vice-president Teodoro Nguema Obiang Mangue’s yachts. The two incidents are linked, said people familiar with the matter who declined to be identified due to the sensitivity of the situation. They described the arrests — the first involving foreigners in the country’s critical oil sector — as the latest example of the vice-president’s impulsive behavior, which threatens the long-term stability of the Central African state that has been ruled by his father for the past 45 years.