It is not clear if the Russian equipment and personnel are military or contractors, but US officials believe it's all part of the growing signs that Russia is interfering in Libya, according to this official and another US official.
There was some open discussion of this at the Senate Armed Services Committee last week, when the four-star head of Africa Command acknowledged the US believes Russia is trying to manipulate the political outcome in Libya.
General Thomas D. Waldhauser testified: "Russia is trying to exert influence on the ultimate decision of who becomes and what entity becomes in charge of the government inside Libya. They're working to influence that -- that the decision."
Sen. Lindsey Graham then asked about the Russians: "They're trying to do in Libya what they've been doing in Syria?"
Waldhauser answered: "Yes, that's a good way to characterize it."
CNN spoke to officials in Egypt about an earlier Reuters report alleging the placement of drones and special forces in Egypt near the Libyan border.
An Egyptian military official, speaking to CNN on the condition of anonymity, denied the presence of Russian troops on Egyptian soil, but declined to comment further saying the issue is a matter of sovereignty.
Dmitry Peskov, spokesman for Russian President Vladimir Putin, responded to CNN questioning about drones, saying "we don't have that information." On special forces in Egypt near the Libya border he added, "we also have no information about that."
Five years after the fall of Moammar Gadhafi, three governments vie for power in Libya, multiple tribes compete for influence and a slice of the country's dwindling oil wealth; while ISIS has gained a foothold in some areas.
Keen to promote stability, the United Nations hastened in a Tripoli-based Government of National Accord (GNA) early last year.
It continues to compete with the Islamist-dominated General National Congress in Tripoli, also known as the Government of National Salvation, and with the previous internationally recognized government, the Council of Deputies, which has set up camp in the east of Libya and backs Gen. Khalifa Haftar, the head of the so-called Libyan army.
This story has been updated to clarify remarks from an Egyptian military official.