US policymakers are scrambling after the ruling military junta in Niger cancelled a mutual security pact that could lead to American forces being expelled, stirring fears of a loss of vital influence to Russia in west Africa.

In a setback for Washington’s counter-terrorism strategy against jihadist groups in the region, Niger announced last weekend that it was revoking the pact, which had been in force since 2012. There are about 1,000 US military and civilian personnel in Niger.

The junta already expelled French troops last December, following a coup in July of 2023 that toppled the democratically elected president, Mohamed Bazoum.

The cancellation of the American pact could mean the closure of US Air Base 201, a $110m facility built in the north of the country in 2018 to conduct drone surveillance of the Islamic State and al-Qaida-affiliated groups in the Sahel, a semi-arid region in the southern Sahara desert stretching from the Atlantic to the Red Sea.

Washington fears the loss of its bases in Niger would risk the country following neighbouring Burkina Faso and Mali by falling under Russian hegemony. The Wagner group, the Kremlin-linked mercenary army formerly headed by Yevgeny Prigozhin, has established a presence in the two bordering states, as well as in several other African countries.

After last July’s coup in Niger, Prigozhin issued a statement welcoming the new military government and offering it Wagner’s services. The US then made its own overtures to the junta earlier this year during a testy visit by representatives from the state department and Pentagon, who hoped to keep cooperation intact after the coup and prevent the country from falling under Russian and Iranian influence.

But on 15 March, in an address on national television, the junta’s spokesman, Colonel Amadou Abdramane, declared the US presence in Niger “illegal” and pointedly depicted the visit – headed by Molly Phee, assistant secretary of state for African affairs – as counterproductive.

“[The military government] forcefully denounces the condescending attitude accompanied by the threat of retaliation from the head of the American delegation towards the Nigerien government and people,” Abdramane said.

The comments were apparently provoked by accusations from US officials that Niger had been conducting negotiations to allow Iran access to its uranium reserves, a development that would potentially enable Tehran to expand its nuclear programme.

“The government of Niger rejects the false allegations of the head of the American delegation to maintain that it has signed a secret agreement on uranium with the Islamic Republic of Iran,” said Abdramane, adding that it was ending the security pact “with immediate effect”.

US officials claim to have since detected a flexibility in Niger’s stance, suggesting that the junta’s hardline posture may still be open to negotiation.

Gen Charles Q Brown, chairman of the joint chiefs of staff, said Nigerien officials had sent “mixed signals” following last weekend’s announcement. “We will continue to make plans and prepare – if we stay or depart,” he told journalists at Ramstein air base in Germany.

A state department spokesman, Vedant Patel, similarly hinted at hopes of achieving a shift through continuing diplomatic dialogue.

“We are remaining in touch with the CNSP [Niger’s ruling military council] and seeking additional clarification of their comments, as well as discussing potential next steps,” he told a news briefing.

“We continue to engage through our embassy. We continue to have our ambassador and our embassy team there, and we’re continuing to discuss with them.”

Crystallising US fears of growing Russian and Iranian influence, the junta’s prime minister, Ali Mahamane Lamine Zeine, visited first Moscow last December to discuss military and economic ties, then Tehran in January, where he met Iran’s president, Ebrahim Raisi.

Air Base 201 is one of the biggest US drone facilities in Africa and the only one in that part of the continent flying drones with intelligence, reconnaissance, surveillance and strike capabilities. It is understood to have been used to carry out deadly strikes against Islamic State fighters in Libya in 2019.

A Pentagon spokesperson said this week that the facility had not been used in counter-terrorism operations since last year’s coup.

Gen Michael Langley, head of the US Africa Command – a member of the recent delegation to Niger – told a Senate armed services committee meeting this month that a continued US military presence in the region was necessary to counter Russian encroachment.

“I’d say that a number of countries are at the tipping point of actually being captured by the Russian Federation as they are spreading some of their false narratives across Libya,” he said. “At [an] accelerated pace, [the] Russian Federation is really trying to take over central Africa, as well as the Sahel.”