The U.S. will not sit still while innocent people are killed in Sudan's Darfur region, Secretary of State Condoleezza Rice said Wednesday, urging an immediate cease-fire and deployment of U.N. peacekeepers.

The top U.S. diplomat said Sudan's government could cooperate with the United Nations or face a confrontation. She warned of consequences if Sudan chose a fight and hinted at further U.N. penalties against the Khartoum government or rebel groups.

"We're not going to sit by and allow this kind of death and destruction to continue," Rice said during a question-and-answer session after her speech at the Africa Society's National Summit on Africa. "We'll use whatever tools are necessary, through the U.N, to be able to stop that."

Fighting between government-backed Arab militias and non-Arab rebels in Darfur has left more than 200,000 dead and 2.5 million displaced since 2002.

More than two years have passed since the Bush administration labeled the atrocities in Sudan as genocide. But the killing has accelerated in recent weeks as the Sudanese government has launched a new offensive.

A poorly funded African Union force in Darfur has been unable to contain the violence and the U.N. Security Council has sought to take over the operation to provide better resources. Sudan opposes such a step.

"I would hope that the message that is going out to Sudan, not just from us but from every country in the world, is that this is now a real fork in the road," Rice said.

President Bush used his address to the U.N. General Assembly last week to announce a new envoy for Sudan and to decry the violence. Rice's address Wednesday was the most comprehensive high-level assessment of the problem to date.

In her speech, Rice said that long-term stability and safety for people in Sudan will come only when the many overlapping political and factional fights are addressed. She accused Sudan's government of hoarding wealth and power at the expense of much of the rest of the country, Africa's largest and about the size of the U.S. from east of the Mississippi River.

Rice said that if Sudan "works with the United Nations and welcomes a U.N. force into Darfur then it will find a dedicated partner in the United States."

Bush has told Sudanese President Omar el-Bashir that the U.S. was prepared to examine all aspects of its relationship with Sudan, Rice said. U.S. lawmakers are close to approving penalties against Khartoum.

"If the Sudanese government chooses confrontation — if it continues waging war against its own citizens, challenging the African Union, undermining its peacekeeping force and threatening the international community — then the regime in Khartoum will be held responsible and it alone will bear the consequences," Rice said.