Hillary Clinton: "Backsliding by any party will be met by credible pressure"
US President Barack Obama has offered "incentives" to Sudan, if it acts to improve the situation in Darfur.
However, as he unveiled a new policy on Khartoum, Mr Obama threatened "increased pressure" if Sudan failed to make progress towards achieving peace.
Secretary of State Hillary Clinton said the US was still focused on addressing the effects of "genocide" in Darfur - a term Sudan said was "unfortunate".
The UN estimates that 300,000 people have died in Darfur since 2003.
In a statement, Mr Obama said: "If the government of Sudan acts to improve the situation on the ground and to advance peace, there will be incentives.
"If it does not, there will be increased pressures imposed by the United States and the international community."
He said the world must act "with a sense of urgency and purpose" on Sudan.
"First, we must seek a definitive end to conflict, gross human rights abuses and genocide in Darfur. Second, the Comprehensive Peace Agreement between the North and South in Sudan must be implemented to create the possibility of long-term peace".
In his statement, Mr Obama said he would renew tough measures against Khartoum later this week.
The US has stressed the new approach does not mean it will deal directly with Sudanese President Omar al-Bashir, says the BBC's Kim Ghattas in Washington.
James Copnall, BBC News, Khartoum
There had been a fierce debate in the US on how to deal with Sudan - President Bashir and his party are regarded by many with real distaste.
The new policy seems to have softened previously hard edges - but not so much as to completely infuriate the anti-Khartoum lobby in America.
The word "genocide" is intensely annoying to Mr Bashir's camp, it seems sanctions are to be renewed, and the warnings about "credible, meaningful disincentives" if progress is not made will not please, either.
But the offer of "incentives" and engagement would not have been made by an American administration a few years ago.
Mr Bashir is wanted on an international arrest warrant for crimes against humanity in Darfur.
Mrs Clinton said the US remained intent on "reversing the dire human consequences of genocide" in the Darfur region by addressing problems in refugee camps and protecting civilians from attack.
She said Washington's engagement with Sudan would hinge on the provision of a safe haven for refugees.
"We are looking to achieve results through broad engagement and frank dialogue," she said.
Sudan has said the new US strategy is an improvement on the previous US stance.
"Compared to previous policies there are positive points, we don't see the extreme ideas and suggestions which we used to see in the past," said senior presidential adviser Ghazi Salaheddin
"I will say it is a strategy of engagement, not a strategy of isolation."
But he said the use of the word "genocide" to describe the situation in the Darfur region was "unfortunate" and "does not reflect the realities in Darfur".
The Obama administration will no doubt face criticism from human rights group, who oppose engagement with Sudan because of the indictment against Mr Bashir, says our correspondent.
It also remains unclear what incentives the US is offering and what the consequences will be for Sudan if the situation does not improve, she adds.
The Darfur conflict began in 2003 when rebel groups attacked government targets, accusing Khartoum of oppressing black Africans in favour of Arabs.
Pro-government militiamen hit back with brutal force, which the US and some rights groups have labelled genocide.
Khartoum denies supporting the militias, but the international court in The Hague issued an arrest warrant earlier this year for Mr Bashir, accusing him of war crimes.
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