Russian military personnel have entered an air base in Niger that is currently hosting U.S. troops, according to a senior U.S. defense official who spoke to Reuters. The move follows a decision by Niger's ruling junta to expel U.S. forces from the country, which had been a key partner for Washington's fight against insurgents in the region until a coup last year.

The U.S. defense official, speaking on condition of anonymity, stated that Russian forces are not mingling with U.S. troops but are using a separate hangar at Airbase 101, located next to Diori Hamani International Airport in Niamey, Niger's capital. The presence of Russian and U.S. troops in close proximity at a time of heightened military and diplomatic rivalry between the two nations, particularly over the conflict in Ukraine, has raised concerns about the future of U.S. installations in the country following a withdrawal.

"(The situation) is not great but in the short-term manageable," the official said, while the Nigerien and Russian embassies in Washington did not immediately respond to requests for comment.

The U.S. and its allies have been forced to move troops out of several African countries following coups that brought to power groups eager to distance themselves from Western governments. In addition to the impending departure from Niger, U.S. troops have also left Chad in recent days, while French forces have been kicked out of Mali and Burkina Faso.

Meanwhile, Russia is actively seeking to strengthen its relations with African nations, presenting itself as a friendly country without colonial baggage. Mali, for example, has become one of Russia's closest African allies in recent years, with the Wagner Group mercenary force deploying there to fight jihadist insurgents.

According to the U.S. official, Nigerien authorities had informed the Biden administration that about 60 Russian military personnel would be in Niger, although the official could not verify that number. After the coup, the U.S. military moved some of its forces in Niger from Airbase 101 to Airbase 201 in the city of Agadez, which has been used since 2018 to target Islamic State and al Qaeda affiliate fighters with armed drones.

Washington is concerned that Islamic militants in the Sahel region may be able to expand without the presence of U.S. forces and intelligence capabilities. The decision by Niger's junta to ask for the removal of U.S. troops came after a meeting in Niamey in mid-March, during which senior U.S. officials raised concerns about the expected arrival of Russian forces and reports of Iran seeking raw materials in the country, including uranium.

While the U.S. message to Nigerien officials was not an ultimatum, the official said it was made clear that U.S. forces could not be on a base with Russian forces. "They did not take that well," the official added.

A two-star U.S. general has been sent to Niger to try and arrange a professional and responsible withdrawal. Although no decisions have been made regarding the future of U.S. troops in Niger, the official said the plan is for them to return to U.S. Africa Command's home bases in Germany.

The intensifying military cooperation between Russia and Niger has been a central point of contention between the U.S. and the Nigerien junta, according to CNN. Russia and Niger agreed to strengthen their military ties in January, with Russian media reporting on April 11 that Russia was sending equipment and 100 military trainers to Niger, although one source said Russian troops were in the country well before April.

As the U.S. military works with Nigerien officials to carry out an orderly withdrawal of troops from the country, the Pentagon has confirmed that it will be sending another delegation to Niger "hopefully ... this week" to further discuss the withdrawal. The U.S. is still trying to get clearance from the Nigerien government for military flights in and out of the country.