Washington( CNN) US aerial reconnaissance assets have recently noticed both Russian transport aircraft and a large Russian droning at an airbase in far western Egypt close to the Libyan border, CNN has learned.

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 Service 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.