Practice makes perfect. Americans and Brits are heading into battle … in cyberspace. The plan, arranged during Prime Minister David Cameron’s current U.S. visit, is to simulate attacks on the financial hubs of both countries to test how they share information. The first battle takes place later this year, with subsequent skirmishes to check the security of national grids. New “cyber cells” of FBI and MI5 agents are teaming up — an unprecedented partnership — to help ensure victory in case of a real cyber war.