Niger mediation efforts appeared stalled on Wednesday after the leaders of a July coup rejected another diplomatic mission, and neighbouring allies who back the armed takeover appealed to the United Nations to prevent a military intervention.

Niger’s junta denied entry to a joint delegation from African countries and the United Nations on Tuesday, resisting pressure to negotiate ahead of a summit on Thursday in which the main regional bloc, the Economic Community of West African States (ECOWAS), will discuss possible use of force.

The move has dimmed hopes of a diplomatic resolution to the standoff that threatens to further destabilise West Africa’s Sahel region – one of the world’s poorest that is already dealing with a string of coups and a deadly Islamist insurgency.

Neighbouring Mali and Burkina Faso, also ruled by military juntas, asked the U.N. Security Council in a letter on Tuesday to prevent any armed action against Niger, saying it would have “unpredictable” consequences and lead to the break-up of ECOWAS.

“The Transitional Governments of Burkina Faso and the Republic of Mali appeal to the primary responsibility of the Security Council… to use all means at its disposal to prevent armed action against a sovereign state,” said the letter signed by both countries’ foreign ministers and posted on X by the Malian foreign ministry.

They said they were committed to finding solutions through diplomacy and negotiation, but did not give details.

Mali and Burkina Faso had previously vowed to come to Niger’s defence if the regional bloc intervened, saying they would consider that a declaration of war against them.

U.S. Secretary of State Antony Blinken said late on Tuesday that he had spoken to ousted Niger President Mohamed Bazoum to express continued efforts to find a peaceful resolution to the crisis.

“The United States reiterates our call for the immediate release of him and his family,” he posted on the social media platform X, formerly known as Twitter. Bazoum has been detained in his residence since the July 26 coup.

Nigeria’s President and ECOWAS chairman Bola Tinubu imposed more sanctions on Tuesday aimed at squeezing entities and individuals involved in the takeover, and said all options were still on the table.

ECOWAS has said that the use of force would be a last resort if the soldiers do not step down and free Bazoum. The bloc’s defence chiefs have agreed on a possible military action plan, which heads of state are expected to consider at their summit in the Nigerian capital, Abuja.

Recent coups in West and Central Africa

BURKINA FASO

Burkina Faso’s army ousted President Roch Kabore in January 2022, blaming him for failing to contain violence by Islamist militants.

Coup leader Lieutenant Colonel Paul-Henri Damiba pledged to restore security, but attacks worsened, eroding morale in the armed forces leading to a second coup eight months later when current junta leader Captain Ibrahim Traore, seized power in September following a mutiny.

MALI

A group of Malian colonels led by Assimi Goita ousted President Ibrahim Boubacar Keita in August 2020. The coup followed anti-government protests over deteriorating security, contested legislative elections and allegations of corruption.

Under pressure from Mali’s West African neighbours, the junta agreed to cede power to a civilian-led interim government tasked with overseeing an 18-month transition to democratic elections in February 2022.

But the coup leaders clashed with the interim president, retired colonel Bah Ndaw, and engineered a second coup in May 2021. Goita, who had served as interim vice president, was elevated to the presidency.

ECOWAS lifted some of the sanctions on Mali after the military rulers proposed a two-year transition to democracy and published a new electoral law. The country is scheduled to hold a presidential election in February 2024 to return to constitutional rule.

CHAD

Chad’s army took power in April 2021 after President Idriss Deby was killed on the battlefield while visiting troops fighting rebels in the north.

Under Chadian law, the speaker of parliament should have become president. But a military council stepped in and dissolved parliament in the name of ensuring stability.

Deby’s son, General Mahamat Idriss Deby, was named interim president and tasked with overseeing an 18-month transition to elections.

The unconstitutional transfer of power led to riots in the capital N’Djamena that were but down by the military.

GUINEA

Special forces commander Colonel Mamady Doumbouya ousted President Alpha Conde in September 2021. A year earlier, Conde had changed the constitution to circumvent limits that would have prevented him from standing for a third term, triggering widespread rioting.

Doumbouya became interim president and promised a transition to democratic elections within three years.

ECOWAS rejected the timeline and imposed sanctions on junta members and their relatives, including freezing their bank accounts. The military regime has since proposed to start the 24-month transition in January 2023, but opposition parties say it has done little to put in place institutions and a roadmap to return to constitutional rule.