Still no real clarity on who was behind the recent vicious attack against African Union peacekeepers in Haskanita that left about a dozen Nigerian soliders dead and the future of the joint U.N./A.U. force in jeopardy, but here's where we are:

Two Sudanese rebel groups are suspected of being behind the attack, a source close to the investigation in Sudan said Tuesday.

"It could be a combined attack by the Sudan Liberation Movement SLM-Unity of Abdhallah Yahia and another group which recently split from the Justice and Equality Movement (JEM)," the source said on condition of anonymity.

The source declined to say what the suspicions were based on.