Clooney, just back from a visit to the region, described how he secretly traveled across the border, came under rocket attack and witnessed death and destruction in the African countries. He recalled how a 9-year-old boy had his hand blown off.
"What we're looking at is a real disaster," Clooney told a small group of reporters before testifying at a Senate Foreign Relations Committee hearing.
Traveling with John Prendergast, the co-founder of the advocacy group the Enough Project, Clooney filmed the hardship for a video that was posted online shortly before his testimony.
The Academy Award-winning actor brought his star power to an issue that the committee chairman, Sen. John Kerry, D-Mass., acknowledged captures the public's attention only intermittently.
After more than two decades of fighting, South Sudan seceded last July and became the world's newest country. But violence has raged along the border since then, and the two countries have been at odds over oil located in South Sudan but shipped through pipelines in Sudan. Disputes have halted oil shipments, a blow to China, which receives 6 percent of its oil from Sudan and now must find other sources.
Clooney acknowledged a "misery fatigue" for Americans amid the war in Afghanistan and crises in Syria, Somalia and elsewhere as he tries to raise awareness about the suffering in South Sudan. But he pointed out that President Barack Obama cited the shutdown of oil in the Sudan region as contributing to the rise in gas prices, and a resolution of the conflict could affect Americans at the pump.
At the hearing, Princeton Lyman, the U.S. special envoy on Sudan, described a deteriorating situation.
Clooney planned to meet with Obama and Secretary of State Hillary Rodham Clinton on Thursday.
