Senior U.S. and NATO officials reported Friday that the alliance is running out of some bombs in Libya—which could mean the U.S. may have to return to the conflict. After the U.S. commandeered the early part of the Libyan airstrikes, NATO—led by Britain and France—has since taken over the campaign at the U.S.’s urging. But despite the intense support by British and French leaders for the campaign, the lack of munitions, including precision bombs and aircraft, shows their limitations. NATO commanders have not asked the U.S. to come back, but NATO officials admitted they can’t keep up with the pace of the bombing. Meanwhile on the ground, rebels and Human Rights Watch reported that Col. Muammar Gaddafi’s troops had used cluster bombs against civilians.