China and Russia are being accused by Amnesty International of supplying arms to Sudan, that are then used in Darfur. The report says the weapons end up with the government-backed militia, the Janjaweed, who have been fighting rebels and slaughtering innocent civilians for four years. Sudan denies it, while China and Russia aren't commenting, but Amnesty's photographic evidence is certainly compelling.
China and Sudan have been close allies for a while; China uses Sudanese oil to help its fast-growing economy, and in return pretty much ignores what Sudan does in Darfur. The main reason why so little's been done about Darfur at the UN over the years is because the Chinese don't want to upset the Sudanese by agreeing to something they won't like, such as lots of international troops to go and protect the civilians. Even though agreement has been reached for a small UN force, there's still no sign of it actually materialising. China could lean on Sudan and make sure the peacekeepers get to Darfur, but chooses not to. If things are going to improve for the people left in Darfur, Russia and particularly China have got to stop sending arms, and start putting pressure on the Sudanese government to accept what the rest of the world knows is needed.