Led by a Russian national from some reports, in constant contact with Moscow and likely funded and supplied by Moscow
There are four separate major Rebel commanders, and they don’t cooperate or coordinate very well. Strelkov/Girkin is a Russian Nationalist, while Bezler is a Ukrainian-born Russian. Mogiliev (sp?) is also a Ukrainian Russian. I don’t know much about the 4th.
It is clear that while Russia is supporting them, especially civilian Russia (Bezler has a BIG Russian-language Social Media fundraising operation) that really wasn’t any more than a “wink,wink” kind of thing until on or about June 27, when it became clear the Kiev was using the ceasefire-that-wasn’t-actually-a-ceasefire to gather huge forces against the rebels.