Defense Secretary Robert Gates said civilian casualties in Afghanistan were posing a strategic challenge to U.S. battlefield success there, a sign of the mounting American concern that civilian deaths are leading ordinary Afghans to turn against the coalition and shift their support to the Taliban. Mr. Gates said U.S. Gen. Stanley McChrystal, who commands all coalition forces in Afghanistan, believes that continued Afghan casualties at the hands of American and North Atlantic Treaty Organization forces imperiled the entire war effort there. "[Gen. McChrystal's] view is that the civilian casualty question is a strategic question in Afghanistan," Mr. Gates told reporters traveling aboard a military plane en route to Latin America. "He thinks that is one of the biggest risks to the success of our strategy." Mr. Gates also had harsh words for WikiLeaks, a whistleblower Web site which last week released military video footage of U.S. pilots killing a pair of Reuters journalists in Baghdad several years ago. WikiLeaks said it would release new videotapes Tuesday showing that U.S. warplanes failed to follow proper safeguards when they bombed suspected insurgent positions near Farah, Afghanistan, last year, killing dozens of Afghan civilians. Mr. Gates said the WikiLeaks videos were misleading because they failed to show the events which took place immediately before the U.S. strikes. "These people can put (out) anything they want and are never held accountable for it," he said. "You're looking at a situation through a soda straw, and you have no context or perspective." The initial WikiLeaks video brought new attention to the issue of civilian casualties in Iraq and Afghanistan, a main cause of public anger in the two countries. The continuing deaths are particularly controversial in Afghanistan, where numerous civilians have been killed by U.S. and North Atlantic Treaty Organization forces in recent weeks. Gen. McChrystal has tried to reduce the number of civilian deaths by implementing strict new guidelines restricting the use of air power and other heavy weaponry in populated areas and making it more difficult for NATO commanders to authorize night raids and forced searches of Afghan homes. The United Nations said earlier this year that the number of Afghan deaths at the hands of U.S. and NATO forces had declined considerably, suggesting that Gen. McChrystal's rules were having an impact. But the problem has not gone away completely. Early Monday morning, U.S. forces operating near the southern Afghan city of Kandahar opened fire on a passenger bus, killing four Afghan civilians. In mid-February, a disputed Special Operations raid in Gardez resulted in the deaths of five Afghans, including a pair of pregnant women. NATO and the Afghan government opened formal investigations into the February 12th assault on Gardez after local villagers accused American forces of trying to cover up the incident by removing bullet casings and tampering with the scene of the shootings. Mr. Gates said he'd been told that the allegations of a cover up there were "questionable," but said U.S. and NATO commanders would punish any troops who were found to have violated battlefield guidelines designed to minimize civilian casualties. "In Gardez, if somebody needs to be held accountable or if something happened that shouldn't have happened, then I think appropriate action will be taken," he said. The defense chief also expressed hope that the new government of Kyrgyzstan, which took power after a popular uprising last week, would allow U.S. planes to resume flights in and out of the sprawling Manas air base, a key staging area for troops and supplies bound for Afghanistan. U.S. commanders halted those flights late last week, but Mr. Gates said he believed the Kyrgyz leaders had a "willingness" to keep Manas open and to clear the way for full operations to resume there.(WSJ)