Ivan Moiseyev, head of Russia's Space Policy Institute, said "the possibility of a collision or some kind of interference is extremely small."
Intelsat said it had unsuccessfully tried to contact the operator of the Luch relay satellite.
"Despite direct and indirect inquiries by the appropriate regulatory bodies and governmental agencies, the operator of the other satellite was unresponsive," it said in a statement to the BBC.
Intelsat Inc. operates about 50 satellites, some of which are used by the US military, including for drone missions and communications with "remote military outposts."
Moiseyev said the Luch "is simply a relay satellite, sending signals from spacecraft to Earth, for example from the International Space Station (ISS) – we have communications problems there – and from one satellite to another."
"In no way can it be an 'aggressor,'" he told RIA Novosti. "Any satellite can make some clumsy maneuvers, but collisions are extremely rare."
In June, the Luch satellite positioned itself in between two Intelsat satellites, where it remained until September. During that time, the Luch came within six miles of one of the other satellites, which is very close in space terms.
A US space expert, Brian Weeden, told BBC there was no danger of a collision between the satellites.
Intelsat said it had "contacted the appropriate regulatory bodies and governmental agencies to express our concern and to ask them to reach out to the operator to correct the situation."