Russia, alongside Egypt and the UAE, backs eastern Libya commander Khalifa Haftar, whose fighters have been battling the forces of Libya's internationally recognized government, which is supported by Turkey.
Libya has been beset by chaos since the overthrow and killing of its long-serving ruler Muammar Gaddafi following a NATO operation in 2011.
The conflict has escalated into a regional proxy war fueled by foreign powers pouring weapons and mercenaries into the country.
Tensions escalated further last year after the Libyan National Army under Haftar moved toward Tripoli to seize the city.
A big escalation in Libya could risk igniting a direct conflict among the foreign powers that have poured in weapons and fighters in violation of an arms embargo.