Air Force Secretary Deborah Lee James said Tuesday that she has not seen a formal proposal for a possible A-10 replacement, but is concerned about the cost of the effort, which the service reportedly briefed to representatives from several think tanks last week. Aviation Week first reported last week that service officials had briefed several think tanks on a preliminary plan to replace the A-10 Warthog's close-air-support capabilities with two parallel development efforts -- one a low-end, light attack...