By George Clooney and John Prendergast  The largest conventional war on the face of the earth in 2011 will occur in Sudan unless bold diplomacy led by the U.S. prevents it. The most dangerous tripwire will be in seven months, when southern Sudanese will vote to determine whether the South splits off and forms a new country. Some ruling party officials don't want to give up the oil-rich South without a fight. Southerners spilled a great deal of blood to win the right to opt out of Sudan, and they will keep fighting until they have their own state.  The last North/South war that ended in 2005 cost more than 2 million lives, and the Darfur conflict in Sudan's West has claimed over 300,000 more. Massive death tolls are the result of war tactics — principally by the government — that target civilians. Communities throughout Sudan have fought an authoritarian government to share in the country's power and wealth.  The good news is that this path to all-out war is unfolding in slow motion, and there is time to prevent it. The U.S. has a history of leading international efforts in Sudan, including helping to broker the 2005 peace deal. But the Obama administration has not taken a direct, leading role in the negotiations to avert renewed war in the South or to end the Darfur conflict. Furthermore, some U.S. officials believe that the United States has no leverage in Sudan.  Because of international sentiment that opposes sanctions and other forms of pressure, the U.S. shies away from creating any real consequences for Sudan's war crimes. And because activists and Congress strongly favor imposing such consequences, U.S. officials avoid serious discussion of peace incentives. We know; we've been a couple of those activists.  U.S. officials can break out of this box and build leverage in support of peace by presenting a Door 1 vs. Door 2 scenario, in which good outcomes would result from peace, and serious consequences would be triggered by war. Parallel carrots and sticks are the key to this approach.  On the carrots side, the U.S. should present a quid pro quo with an expiration date by the end of the year: In exchange for peace in Darfur and the South, the U.S. would move to normalize relations with Sudan and work in the U.N. Security Council to suspend the war crimes indictment of President Omar Hassan al-Bashir under Article 16 of the International Criminal Court charter. On the sticks side, a U.S.-led initiative should build international support for severe consequences for anyone promoting war, whether they are ruling party officials, militias, rebels, or southern Sudan's leaders.  Sudan's ruling party spoilers are supported by Egypt and China, which are interested in the uninterrupted flow of the Nile River and oil, respectively. President Obama should send a senior envoy to Cairo and Beijing to develop a strategy to influence officials in Khartoum and Juba to support peace, ensure oil investments and keep the Nile waters flowing.  Obama should deploy a team of experienced diplomats to revitalize negotiations in support of peace in Darfur and on the issues that continue to divide the North and South, particularly oil wealth sharing.  We believe the challenge in Sudan — with its major humanitarian implications — is precisely the kind of problem that requires the president's direct and imaginative engagement. Helping to shepherd a new state in southern Sudan and a peace deal in Darfur would be a defining achievement of the Obama presidency. Failure in the form of renewed war and hundreds of thousands more deaths — conservatively — is not an option. We often find ourselves looking at humanitarian crises and wondering what we can do to help. This is a moment where we can contribute to stopping one before it happens.  George Clooney is an actor and co-founder of Not On Our Watch. John Prendergast is co-founder of the Enough Project and co-author with Don Cheadle of the forthcoming book The Enough Moment.  You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference.
The Obama administration has the ability to lead the diplomacy that can prevent a humanitarian catastophe. But will the president act?...