Mr. Zoellick's Sudan trip, his third so far this year, will have a dual purpose. He'll represent the United States at Saturday's installation of the new Sudanese government of national unity, effectively ending Sudan's two decade-long north-south civil war.
But the Khartoum stop will be preceded by another visit to Darfur, where the deputy secretary will try to advance the peace process there following Tuesday's agreement in Nigeria.
At the African Union-mediated talks in Abuja, the Sudanese government and the two Darfur rebel groups reached a 17-point framework for wealth and power-sharing, aimed at settling the Darfur conflict along the lines of the north-south peace accord finalized in January.
The Abuja declaration, among other things, calls for an end to hostilities, the return of Darfur refugees and new security arrangements, and it sets longer term goals such as devolving power to Sudanese regions and recognizing tribal land ownership rights in Darfur.
At a news briefing, State Department Spokesman Sean McCormack congratulated the Darfur parties, African Union mediators and Nigeria for hosting the talks.
Mr. McCormack appealed for an immediate end to violence by all groups in Darfur, and urged an early start to negotiations aimed at turning the principles into a tangible agreement for peace and reconciliation:
"What is important now that they have this framework, this declaration of principles, is that they actually start filling in the details of this," said Sean McCormack. "We urge the parties to abide by the principles which they have signed, and keep up the momentum so as to start to work on some of the tough issues ahead. This is a preliminary step, a positive step, but there is a lot of work left to do."
The Darfur conflict began in early 2003 when the rebel Sudan Liberation Army, the SLA, and the smaller Justice and Equality Movement, or JEM, took up arms, accusing the Islamic government in Khartoum of discrimination and neglect.
Khartoum authorities responded by backing a scorched-earth campaign by Arab militiamen in the mainly black-African region. Tens of thousands of people have been killed and some two million displaced in what the United States last year termed genocide.
In a talk with reporters Tuesday, Deputy Secretary Zoellick, the Bush administration's diplomatic point-man for Sudan, said the fighting in Darfur has diminished of late, as has the mortality rate among displaced people as food aid flows to refugee camps.
But he said the militiamen and rebels have not disarmed, and described the situation in Darfur as a fragile equilibrium.
Mr. Zoellick said that after flying into Sudan late Thursday, he will go to the Darfur regional center of El-Fasher early Friday and also visit two towns controlled by the SLA rebels.
He said he will meet with leaders of the African Union monitoring force in the area as well as displaced people and international aid workers.
Mr. Zoellick said he expects to meet with key officials of the Sudanese government and southern rebel leader John Garang on the sidelines of the unity government events in Khartoum Saturday.
Mr. Garang becomes Sudan's first vice-president under the unity government, which will run the country for a six-year interim period leading to a vote on possible independence for the south.
The deputy secretary of state said he will also raise in Khartoum the issue of the Lord's Resistance Army, or LRA, a brutal Ugandan rebel group that Ugandan officials allege has gotten safe-haven in the past in southern Sudan.
Sudan now says it considers the LRA, notorious for battlefield atrocities and the kidnapping of children, its enemy.
Mr. Zoellick said Ugandan forces are making inroads against the group, and that Sudan is allowing Ugandan forces to pursue LRA fighters in its territory.
But he said he would like to see more of a tripartite effort among the Sudanese government, Mr. Garang's Sudan Peoples Liberation Movement, and Ugandan authorities, to put a stop to the LRA, as he put it, for good.