U.S. troops and the Russian military have been nearly operating side-by-side in the African country of Niger for several weeks as tensions over fighting Islamic extremists heat up in the region, officials said.

Russian military personnel have entered an air base in Niger that is hosting U.S. troops, a senior U.S. defense official told Reuters, a move that follows a decision by Niger's junta to expel U.S. forces.

Russian and US troops have been operating out of the same military base in Niger for at least several weeks, a US defense official and another source familiar with the matter told CNN, putting the two militaries in close proximity to each other at a time of heightened tensions over the war in Ukraine and as the country’s ruling junta has made clear it wants US forces to leave.