President Obama, Prime Minister David Cameron, and President Sarkozy issued a joint statement Friday that NATO operations will continue until Gaddafi is out of power. "So long as Gaddafi is in power, NATO must maintain its operations so that civilians remain protected and the pressure on the regime builds,” read the statement, published in European newspapers as an opinion column. While it's the most direct link between the NATO mission and Gaddafi's departure so far, the statement does not specify what sort of operations are going to continue. U.S. officials said they hope the threat of a prolonged NATO campaign would pressure members of Gaddafi's inner circle to force him out. The joint statement could also increase pressure on NATO allies who have so far been reluctant to contribute to the airstrikes. Meanwhile, no NATO members have volunteered the aircraft requested by U.S. Adm. James Stavridis for the NATO campaign.