There was good news last week from the United Nations - as shocking as that may seem.

The U.N. Security Council voted last Tuesday to send 26,000 peacekeepers to Darfur in western Sudan, where government-sponsored militias have been terrorizing the population for the past four years. It will be the largest peacekeeping force in the world - and, at $2 billion a year, reasonably well-funded.

All of which suggests that the force might actually do some good.

The truth is, U.N. forces in Africa have a long history of rather mixed results.

Take Rwanda or Somalia, where peacekeepers utterly failed to prevent horrible mass slaughter. It's hard to keep the peace where there's no peace to keep, especially with rules of engagement that make weapons hardly more than props.

And that's where peacekeepers aren't actively aggravating the conflict. Human Rights Watch has accused U.N. forces policing several recent African conflicts of widespread looting, gun running and rape.

So will Darfur be any different?

Maybe: The new peacekeepers have a mandate that makes them more than spectators - they're actually authorized to use force!

On the other hand, the Security Council resolution isn't nearly as strong as it could have been - thanks mostly to Sudan ally China's veto power. Peacekeepers are not authorized to disarm militias, and threats of sanctions if Sudan doesn't cooperate have been stripped.

Make no mistake: Sudanese President Omar Hassan al-Bashir is a butcher. If he's not forced to rein in the militias, it's highly unlikely that he will.

But the facts on the ground are this: 200,000 people have been killed in Darfur since fighting began in 2003, and a whopping 2.5 million have fled their homes. The several thousand African Union peacekeepers in place since 2004 haven't been able to stop the violence.

A beefed-up U.N. force with a license to kill couldn't do much worse.

So there's reason to hope. But now it's up to Secretary-General Ban Ki-Moon to make sure that Darfur doesn't become yet another U.N. embarrassment.