Military officers in Gabon said they were seizing power Wednesday, just minutes after President Ali Bongo was declared the winner of a controversial election marred by violence and allegations of vote rigging.

The officers who appeared on state television Wednesday announced the closure of borders and dissolved state institutions including the Senate, National Assembly and Constitutional Court. They said in a later statement that Bongo was under house arrest.

Bongo, who was seeking a third term in office, came to power following the death of his father, Omar Bongo, in 2009, after more than four decades in power. Both men were key allies of the oil-rich country’s former colonial power, France, and the family is believed to have amassed significant wealth — which is the subject of a judicial investigation in France.

Gabon is generally considered more stable than other countries that have experienced unrest in recent years, but it now appears set to join a growing list of junta-led states – including Burkina Faso, Chad, Guinea, Mali and Sudan — that create a geographical belt of turmoil across sub-Saharan Africa.

Niger

Rebel soldiers in Niger deposed the country’s Western-allied president, Mohamed Bazoum, on July 26 amid political upheaval, a rise in Islamist extremism and growing Russian influence across the region.

Britain, France, Germany and the European Union announced the end of aid to Niger after the ouster, and Secretary of State Antony Blinken said the United States could follow suit. So far, President Biden has not labeled the situation a coup.

A key regional bloc, the Economic Community of West African States (ECOWAS), said in August that it was prepared for military intervention and had decided on a “D-Day” for intervention – though it did not give a date and said diplomacy was still possible.

Coup supporters in Niger’s capital, Niamey, as well as in neighboring Burkina Faso and Mali, have been spotted waving Russian flags, and experts say uncertainty around the coup leaders’ motivation may hamper Western attempts to restore Bazoum through diplomacy.