Despite endless rounds of shadowboxing with the dodgy Sudanese government over the ongoing nightmare in Darfur, United Nations Secretary-General Ban Ki-Moon is asking us to give appeasement, er, diplomacy, one more chance.

That's not going to help: It's going to take some highly credible threats to get Sudan's President Omar al-Bashir to end what many call the 21st century's first genocide.

What kind of threats? Before I detail that, let's review why diplomacy alone is a guaranteed bust.

The U.N. attempts to stop Khartoum's ethnic cleansing have been feckless. At last count, the campaign by Sudanese government forces and their Arab-Muslim "Janjaweed" henchmen against Muslim Africans in Darfur has left 200,000 dead, 2 million refugees and 4 million needing assistance.

Bashir has made a mockery of U.N. efforts to stem the violence since the Security Council passed its first resolution on Darfur in 2005.

He's made promise after promise to stop the chaos and carnage, yet it continues unabated. Now the ever-worsening humanitarian disaster is spilling over Sudan's borders into neighboring Chad and the Central African Republic.

Last week, a "confidential" U.N. report disclosed that Khartoum is still moving weapons into Darfur, in violation of Security Council resolutions. Bashir's boys are even disguising Sudanese aircraft to look like U.N. planes. (Khartoum denied all the charges.)

Yet Ban calls for still more diplomacy. Indeed, as the White House was getting ready last week to propose U.S. economic sanctions against the Khartoum regime, Ban frantically waved off the move.

Why? Because - after five months of hemming and hawing - Sudan has (again) reversed itself. It now says it will allow the deployment of a U.N. "heavy-support package" to augment the 7,000 beleaguered African Union troops in Darfur.

Fine. The U.N. Blue Helmets - 3,000 troops and police, plus six helicopter gunships - will support the A.U. Green Helmets. That means a force of 10,000 trying to bring peace and stability to an area the size of Texas.

Of course, the United Nations hopes to add another 10,000 peacekeepers (more appropriately called "peacemakers," since peace doesn't exist). But there's no telling if Sudan will agree to a "hybrid" U.N./A.U. force - or how long it'll take to get boots on the ground. (Sudan is insisting new troops be African, surely so that Khartoum can pull strings with their capitals to guide and limit their operations.)

The initial 3,000 Blue Helmets won't get there until the end of June, at the earliest - assuming Turtle Bay can round up enough brave souls. How many more Darfuris will perish by then? How many more rapes? How many more refugees?

Political reconciliation between Khartoum and the Darfuri rebels - who demand more representation in the central government and wealth-sharing and less discrimination - is fundamental to ending the violence. But that now looks more distant than ever.

Only one of three major rebel groups signed the 2006 peace agreement reached at U.S. urging. Now there are as many as 15 rebel groups - making an inclusive peace agreement a Herculean task.

Can the slaughter be stopped in the meantime? Not with the small U.N. and A.U. forces now proposed - not even if they have a robust mandate (meaning authorization to take offensive action if necessary) under Chapter 7 of the U.N. Charter.

First, a serious effort has to expect more reversals and backsliding by Khartoum on its promises. The United Nations needs to establish firm benchmarks and deadlines for ending the violence, disarming the Janjaweed and starting peace negotiations. (Yes, it's appalling that this hasn't been done yet - welcome to "feel good" international diplomacy.)

Second, back up those deadlines with punitive economic and financial sanctions. If Khartoum fails to meet the benchmarks, hit 'em hard.

Sure, China will run interference for Sudan at Turtle Bay - but a group of like-minded nations could be "cherry-picked" for sanctions duty.

Even without Security Council approval, American and European Union countries, India and Japan could all curtail financial and business dealings with, and investment in, Sudan. They could also freeze the assets of Sudanese officials responsible for the death and destruction in Darfur.

Third, recognize that the current arms embargo is meaningless without international efforts to tighten it.

There will still be smuggling, especially out of Egypt, but better enforcement could hamper Sudanese government and Janajweed militia operations.

This last option requires U.S. military planning. The Pentagon should look at what it would take to set up a no-fly zone over Darfur - probably out of neighboring Chad. No easy proposition, but the mere suggestion of a U.S. - or, better yet, NATO - no-fly zone over Darfur would give Khartoum heart palpitations.

The slaughter in Sudan can be stopped - but only if the world is up for joining the United States in some serious arm-twisting. If other nations don't find the political spine to do so, things are only likely to get worse in Darfur.

Peter Brookes is a senior fellow at The Heritage Foundation and the author of "A Devil's Triangle: Terrorism, WMD and Rogue States."