By Karlee Weinmann (August 12, 2013, 4:46 PM EDT) -- Activist investor Bill Ackman, who sits on J.C. Penney Co.'s board, is under fire from his fellow directors after sending a pair of public letters last week that took aim at the sputtering retailer's leadership and pressed for the ouster of its chairman, the Wall Street Journal reported on Sunday. The board met over the weekend to discuss potential ramifications of Ackman going public with his letters, which detailed confidential boardroom talks. It has remained unclear whether Ackman — well-known for his sharp-tongued critiques of company leadership — had violated his director duties, though his colleagues on the board are assessing their options for moving forward. The board is also reviewing Ackman's proposal to throw out J.C. Penney's current chairman and expedite the search for a permanent CEO....