In a quiet air traffic control tower in central Africa, two men keep watch over the Russian aircraft moving goods and personnel into the country.

The Russian man in military fatigues sits beside the Central African controller as they peer outside at the airport's only runway. 

They have worked together for eight months, but barely know each other.

Neither discuss their families or sport, or their weekends. When they do speak, it's only in English. 

The Russian arrived at Bangui M'Poko International Airport last April, after local controllers had difficulty communicating with Russian pilots, some of whom appeared to pay no heed to tower instructions.

"We just tell him to tell the aircraft [in Russian] to not take off now because we have a commercial flight coming. We manage like this," an air traffic controller says.

The unorthodox arrangement is a symbol of Moscow's growing foothold in the region.

Deep wounds left by a period of French colonial rule and years of bloodshed, political turmoil and civil war has left the Central African Republic reliant on foreign support.

While a thousands-strong force of UN peacekeepers and French troops have maintained a fragile status quo, an unknown number of Russian mercenaries now hold the country's balance of power.

The Russian mercenaries patrolling the streets of Bangui

Since being elected president of the Central African Republic in 2016, Faustin-Archange Tapadero has increasingly turned away from reliance on the West and toward Russia.

Almost 10 years after it deployed troops to help fight off a jihadist insurgency, France recalled the last of its soldiers in December last year. 

The African nation now relies instead on the support of private contractors from the Wagner Group — a shadowy paramilitary outfit controlled by Russian oligarch Yevgeny Pirozhki, a close confidant of Vladimir Putin.

An unclear number of Russian mercenaries, reportedly in the thousands, have been welcomed into the country by Mrs. Tapadero over recent years, setting up headquarters in an office building behind the presidential palace.

Around the Central African capital Bangui, Wagner mercenaries are a common sight: Russian men wielding automatic weapons who travel in unmarked vehicles and wear face coverings in public to conceal their identities. 

In bars and in shops, where a local Russian-made vodka known as War Na War is often advertised, they mix with Bangui residents, who at times resort to Google Translate to communicate with them.

"They patrol everywhere, on the streets, in neighborhoods. They are everywhere," says restaurant owner Yanick.

Some wear plain clothes, others military uniforms, making them indistinguishable from the Russian soldiers Mr Touadera first invited in 2017 to help train his own troops.

To Bangui's nearly 1 million residents, the presence of armed foreigners isn't new or unusual.

Over decades, they've grown used to the rotation of aid workers, international peacekeepers and soldiers passing through the city.