THE GOVERNMENT OF SUDAN has stopped even pretending to cooperate with the international community's efforts to end the ongoing genocide within its borders. So the time has come for the world to stop pretending that Sudan isn't a rogue state and slap it with the harshest possible sanctions.

Just a few months ago, Sudanese officials seemed on the verge of accepting a U.N. peacekeeping force. The U.S. in May brokered a peace deal between the Arab-led government and one of the largest rebel groups in Darfur, raising hopes that a 20,000-strong U.N. force would soon protect Darfurian civilians. An estimated 2 million people have been displaced from the region and 200,000 killed during a three-year bid by government troops and Arab militias to put down a rebellion — or perhaps instigate a campaign of ethnic cleansing against black villagers.

Hopes for peace have now completely evaporated. Since the deal was signed, violence has grown worse; 11 aid workers have been killed, and U.N. emergency relief coordinator Jan Egeland warned Monday that the humanitarian relief effort is on the verge of collapse, threatening hundreds of thousands more with death. The warning comes as the Sudanese government in Khartoum is proposing to openly send 10,000 troops to Darfur, a move that would be seen by the local populace as an invasion and could lead to all-out war.

Meanwhile, Khartoum has turned a deaf ear to all diplomatic entreaties. Its foreign ministers didn't show up Monday at a Security Council meeting on the crisis, and when Jendayi E. Frazer, U.S. assistant secretary of State for African affairs, flew to Khartoum during the weekend with a letter from President Bush to Sudanese President Omar Hassan Ahmed Bashir, the latter refused to show up.

World events have doubtless emboldened Bashir. The United Nations, and global public opinion, are distracted by more urgent efforts to put together a peacekeeping force for the less-deadly situation in southern Lebanon; meanwhile, the U.S. military is overstretched. Sudan sits on large oil reserves, which have turned Khartoum into a bustling city and decreased the country's reliance on the West. China depends heavily on that oil and, along with Russia, has resisted approving intervention without Sudanese permission, or even pressuring Khartoum to grant it.

The time to act is running out. There is already an international force in Darfur — about 7,000 African Union peacekeepers — but they are barely able to defend even themselves, and their mandate expires Sept. 30. The U.S. and Britain have put together a draft resolution for rapid deployment of a U.N. force, but without permission from Sudan, it will probably fail. If that happens, China and Russia will have blood on their hands. How dispiriting — that genocide in our time is met with unconvincing lectures about sovereignty and a weary collective shrug.