The United States urges the governments of Sudan and South Sudan to cease attacking each other across their undemarcated border to avert an all-out war and a looming humanitarian disaster.



"Neither of these countries truly wants a full-scale war. They know that they cannot afford it, and that neither of them can win it. However, given the high emotional pitch of the last few weeks and continued fighting and tensions along the border, there is a risk that they could gravitate toward it," U.S. Special Envoy for Sudan and South Sudan Princeton Lyman said in prepared testimony to Congress April 26, 2012.



South Sudan became an independent country in July 2011 after fighting for more than a half-century against the government in Khartoum. But fighting along the border continues. In April, the Sudanese air force bombed targets in South Sudan as well as inside its own borders, the states of Southern Kordofan and Blue Nile, where people sympathetic to South Sudan live.



"More than 140,000 Sudanese refugees have been displaced from these two states since last June," Lyman said.



The South Sudanese army, for its part, briefly invaded Heglig, an oil-rich region of Sudan, in April, before withdrawing under strong international criticism.



The United States is working with the United Nations, the African Union and the Arab League to support an African-led action plan to end the conflict and bring the parties back to the negotiating table, Lyman said. He added that efforts are being made to involve China in the push for peace.



Political talks between the governments in Khartoum and Juba "must be part of the path to mutual security," Lyman said. "The United States is strongly opposed to, and we continue to condemn, attacks across the border by either side."



The struggle between Sudan and South Sudan has created a humanitarian crisis that could become a catastrophe soon with the arrival of the rainy season. The rains "will make the delivery of humanitarian aid significantly more difficult, more dangerous and more expensive," the envoy said.



The U.S. Agency for International Development said the conflict has displaced, killed or severely affected more than 500,000 people, disrupting harvests, trade and long-term development.



The United Nations, the African Union and the Arab League have offered a proposal for monitored international humanitarian access to the troubled region. The government in Juba has agreed to it, while the authorities in Khartoum have accepted it "in principle," but are withholding support because of questions about its implementation.



Lyman said he was hopeful that the proposed humanitarian assistance program would set the conditions for a cessation of hostilities.



The envoy said he was optimistic that the advocates for peace on both sides of the conflict eventually will prevail. "They may be sidelined from time to time by hard-liners, but they are always present, and I think their impulses better reflect the aspirations of their war-weary citizens," he said.